Whenever any area is annexed to the Municipality, one of the following conditions will apply:
(a) Land that is zoned prior to annexation shall be classified as being in whichever district most closely conforms with the zoning that existed prior to annexation. Such classification shall be recommended for an interim period by the Planning Commission to the Municipal Council, and the Council shall approve the same after public hearing.
(b) Land not zoned prior to annexation shall be classified in the same manner into whichever district of this code most closely conforms with the existing use of the annexed area, or in accordance with the master plan in the case of vacant land.
(c) In all cases, within three months after the effective date of annexation, the Planning Commission shall recommend the appropriate permanent zoning districts for such area to the Municipal Council, and the map shall be amended according to the prescribed procedure set forth in Charter Section 4.11.