The answer is letter A.
Collective nouns could be taken as singular or plural. This depends on how each is used in a sentence. A singular collective noun is a word that functions as a single unit.
For example: The play’s cast is currently rehearsing. The word “cast” is a singular subject. Although there are many members of the cast, they still function as one unit.
The plural collective noun on the other hand indicates many units and thus takes a plural verb.