Collective nouns refer to a group of people, animals or things in a specific manner. In the given sentence, 'crew' is a group of people that work together on the ship. Hence it's a collective noun, and option A is correct. Ship is a common noun that refers to a vessel in which people travel over sea, hence option B is incorrect. Option C is incorrect, as 'strike' is an abstract noun that refers to the stoppage of work by employees in protest. Option D is incorrect because 'ship' is not a collective noun, but it's a common noun.