Based on JavaLatte's answer to this question as well as on various dictionary definitions of the word "respective", I gather that the word serving as the head of a nounphrase premodified by "respective" needs to be plural – but what about the head of a nounphrase containing an "of"-phrase that in turn includes the word "relevant"? Should that always be plural as well? That is, in the following examples, which alternative correct – (a), (b), or both?
a) The chair of the respective committees is responsible for convening meetings
b) The chairs of the respective committees are responsible for convening meetings
I'm thinking that taken together, we're dealing with several chairs (since we're dealing with several committees), but on the other hand, there is (presumably) only one chair for each committee, and we are, after all, talking about each committee separately (I mean, that's the whole point of using "respective" in the first place, isn't it?), so... there seem to be arguments for both alternatives.