Answer:
The correct answer is "Flock"
Explanation:
Collective nouns are words that denote a group of people or things.
In this case, the noun that makes reference to a group of things is "flock".
Flock means a group of birds. In this example it refers to a group of geese.
The rest of the options are incorrext since A) is a singular noun, C) is an adverb and D) is a proper noun.