The question presents the phrase "__ aimez-vous ce film ?" and asks which interrogative word correctly completes it. The answer is Pourquoi (Why).
"Pourquoi aimez-vous ce film ?" means "Why do you like this film?" This is the most natural and meaningful question that can be formed with the verb aimer (to like/love) and a film as the object. Asking why someone likes a film invites them to give reasons for their preference.
The other interrogative words do not produce meaningful questions with aimer in this context:
Ou (Where) - "Where do you like this film?" is not a natural construction. You can ask where someone watched a film, but not where someone likes it.
Comment (How) - "How do you like this film?" is an English pattern that does not translate directly into French with aimer. In French, you would instead say "Comment trouvez-vous ce film ?"
Quand (When) - "When do you like this film?" does not form a coherent question.
