DEFER :

Answer: Option D

Indifferent : having no particular interest or sympathy, unconcerned.
Defy : openly resist or refuse to obey.
Differ : be unlike or dissimilar.
Postpone : cause or arrange for (something) to take place at a time later than that first scheduled.
Defer : put off (an action or event) to a later time; postpone.

Synonym of Defer is Postpone.