Directions: Fill in the blank by choosing the right form of the given four alternatives.

He would have helped you, If you ________ him.

This is a third conditional sentence expressing a hypothetical past situation. The structure is: If + past perfect, ... would have + past participle. The if-clause uses 'had met' (past perfect) because it refers to a past condition that did not happen. The main clause already uses 'would have helped', so the if-clause must match with past perfect.