The correct answer is option (B):
A body of volunteer has been
The correct answer is A body of volunteer has been. Let's break down why.
The phrase "A body of" acts as a singular collective noun. Even though it refers to multiple people (volunteers), grammatically, it is treated as a single unit. Think of it like "a group of," "a team of," or "a committee of." These all take singular verbs.
Therefore, the singular verb "has been" is the correct choice to agree with the singular subject "A body of volunteers."
Let's look at why the other options are incorrect:
A body of volunteer are: This option incorrectly uses the plural verb "are" with the singular subject "A body of volunteers." Also, "volunteer" should be plural here to refer to multiple people.
A body of volunteers were: This option correctly uses the plural noun "volunteers" but incorrectly uses the plural past tense verb "were." Since "A body of" is singular, it needs a singular verb.
The volunteers are: While "The volunteers are" is grammatically correct if you are talking about the volunteers themselves as individuals, it changes the meaning. The original sentence emphasizes the formation of a collective group, which is what "A body of volunteers" conveys. This option removes that nuance and treats the volunteers as a collection of individuals rather than a unified body.