Fill in the blank with a suitable preposition.
Jack and his wife decided to watch a movie _______ cooking.
The preposition ‘at’ is used to speak about an exact time or position. Since cooking is neither a specific time nor a particular place, option A is incorrect. Whereas ‘by’ is used to denote an agent or the end of a particular time period. The sentence doesn’t discuss a period, therefore, option B is incorrect. Similarly ‘within’ refers to a period; 'cooking' is an activity and doesn't denote a period. So option C is incorrect. The preposition ‘after’ is used to speak about an action that follows another action. In the given context when we use the preposition ‘after’ it would mean that cooking is followed by watching a movie, which is appropriate. Therefore option D is correct.