What number should the head noun have in a noun phrase complemented by an of-phrase, where the NP complement of of is headed by a plural noun? Examples:
the development(s) of these theories
the front door(s) of the houses
the ear(s) of the teacups
(I'm assuming here that each individual theory/house/teacup has only one development/front door/ear each).
Is there a rule here, or do we just decide which number to use from one context to another? In that case, based on what?