Complete the scientific journal's summary of Dr. Finklebaum's latest academic disaster.

At the conference, Dr. Finklebaum proposed two entirely absurd theories, _____ made the slightest bit of sense to his peers.

The correct answer is neither of which.

First, because the sentence specifies exactly two theories, we must use the dual quantifier "neither" rather than "none" (which is used for three or more).

Second, to avoid a comma splice, we need a relative pronoun to link the clauses. Since "theories" are things, we use "which". "Neither of them" would create a run-on sentence, and "that" cannot be used directly after a preposition in a non-defining relative clause.