Upon receiving a certified initiatory or referendary petition from the clerk, the council shall, within thirty (30) days, either:
   (a)   if it be an initiatory petition, adopt the ordinance.
   (b)   if it be a referendary petition, repeal the ordinance;
   (c)   or if the council neither adopts or repeals the ordinance, as the case may be, the council shall submit the proposal to the electors.