Sec. 18.6  Benefit amounts. 
   (a)   Normal retirement benefits.  Any employee member eligible for retirement under Section 18.3 hereof, shall upon his own application be retired and shall receive a monthly pension equal to 1/50 of his final monthly compensation for each year, not to exceed twenty-five years of service. Such pension shall be suspended only during the time, if any, such retired fireman or policeman is re-employed full time on either said fire or police force.
   (b)   Disability retirement benefits.  Any employee member eligible for retirement under Section 18.4 hereof shall receive a monthly pension equal to one-half of his final monthly compensation. Any benefits payable under this paragraph (b) shall be subject to the provisions of Section 18.10 hereof.
   (c)   No employee member shall be retired (other than as provided in paragraph (c) of Section 18.3 hereof) except on his own application unless given a full opportunity to be heard in opposition thereto.
   (d)   Duty death benefits.  The amount of the death benefit payable to the estate of the deceased employee member eligible under paragraph (a) of Section 18.5 hereof shall be equal to the sum of one thousand dollars plus his aggregate contributions into the pension fund, reduced by the aggregate pension payments, if any, received by the employee member prior to his death and/or by his dependents (widow or children below eighteen years of age).
   (e)   Non-duty death benefit.  The amount of the non-duty death benefit payable to the dependents of the deceased employee member (i. e., to his widow or children below the age of eighteen years eligible under paragraph (b) of Section 18.5 hereof[,] shall be equal to the sum of eighteen times his final monthly compensation plus his aggregate contributions into the pension fund; provided, however, that such benefit shall be paid in monthly installments (including interest on the unpaid balance at the rate of 3½% per annum) over such period (but not less than thirty-six months) as in the sole discretion of the board of trustees is in the best interests of said dependents. In event the non-duty death benefit is payable to the estate of the deceased employee member, it shall be paid in a lump sum amount equal to the sum of one thousand dollars plus his aggregate contributions into the pension fund.
   (f)   Optional forms of retirement benefits.
      (1)   General provisions relative to options.  Subject to the conditions hereinafter stated, an eligible employee member may, by filing a written request with the city clerk (as agent for the board of trustees) prior to his normal retirement date, elect to receive his pension under one of the optional forms hereinafter set forth in this subsection (f) of Section 18.6. The amount of payments under an optional form shall be the actuarial equivalent, as of the date the option becomes effective, of the pension the eligible employee member would otherwise be entitled to receive.
      (2)   Contingent pension option.  The eligible employee member may elect to receive a reduced monthly pension with the provision that, if his death should occur after the option becomes effective, the designated spouse or child or children under the age of eighteen as contingent pensioner shall receive monthly payments in the same reduced amount (100%), or one-half thereof (50%), as designated in writing by the employee at the time of his election, so long as such contingent pensioner shall survive the employee member.
   In order to elect this option, an eligible employee member must file a written request with the City clerk prior to his retirement date. This option, if elected, shall become effective at the employee member's normal retirement date provided he has made such election at least three years prior to his normal retirement date, or, if made within such three years period, provided he has, at the time of making such election, submitted evidence satisfactory to the board of trustees of his then current good health. If an eligible employee who has elected the option under this subsection within such three year period is unable or unwilling to submit evidence satisfactory to the board of trustees of his then current good health, such option may, at the employee member's election, become effective commencing with the first day of the month following the third anniversary of the date on which the election of this option is accepted by the board of trustees even though the employee member may retire prior to such effective date of the option; provided, however, that both the employee member and his contingent pensioner are alive on said effective date of the option.
   If at the time of the employee member's death the option has become effective, pension payments to the contingent pensioner will commence as of the first day of the month following the month in which the employee member's death occurs, if the contingent pensioner is then living.
   The last pension payment under this option if effective will be the monthly payment due on the first day of the month in which the death of the survivor of the employee member and his contingent pensioner occurs.
   In the event that (i) either the employee member or his contingent pensioner dies prior to the date the option becomes effective or (ii) the monthly amount of pension payment which would become payable to the contingent pensioner is less than ten dollars, or (iii) the employee member does not, prior to the effective date of the option, or within three hundred and sixty days after his election of the option, whichever is earlier, furnish evidence, satisfactory to the board of trustees[,] of the age of his contingent pensioner, the option shall not become effective and pension payments, if any, shall be made as otherwise provided in paragraph (a) of Section 18.6 hereof as if the option had never been elected.
   After an election of the contingent pensioner option has been made and accepted by the board of trustees[,] it cannot be modified or rescinded without the written consent of the board of trustees, which consent will not be given if it would be detrimental to the pension fund.
      (3)   120 month option.  An eligible employee member may, by written application to the city clerk which is received at least three years prior to the date of his normal retirement, elect to convert his normal retirement benefit into an optional form of retirement benefit payable in reduced amount to himself for life but guaranteed in any event for a minimum of one hundred twenty months. The three year advance application requirement may be waived by the board of trustees if it receives satisfactory evidence of the then current good health of the employee member. If an eligible employee member who has elected the option under this subsection within such three year period is unable or unwilling to submit evidence satisfactory to the board of trustees of his then current good health, such option may, at the employee member's election become effective commencing with the first day of the month following the third anniversary of the date on which the election of this option is accepted by the board of trustees even though the employee member may retire prior to such effective date of the option. After an election of the option has been made and accepted by the board of trustees, it cannot be modified or rescinded without the written consent of the board of trustees which consent will not be given if it would be detrimental to the pension fund.
      (4)   Additional optional forms.  The board of trustees may adopt uniform rules granting additional optional benefits which are actuarial equivalents of the benefits normally payable under the plan[,] but such additional options shall be made available only under terms which safeguard the pension fund and do not increase the cost of the retirement system to the city as certified by the actuary under the plan.