He had a strange quirk of hitting his sister every now and then.

Answer: Option C

Fondness : affection or liking for someone or something.
Aversion : a strong dislike or disinclination.
Habit : a settled or regular tendency or practice, especially one that is hard to give up.
Diversion : the action of turning something aside from its course.
Quirk : a peculiar aspect of a person's character or behaviour.

Synonym of Quirk is Habit