In American English, a collective noun used as a unit takes _____ verbs and pronouns.

singular

plural

http://grammar.ccc.commnet.edu/grammar/plurals.htm#collective_nouns

Let me know what you think.

Here's the big clue: "used as a unit"

"a unit" = singular; therefore, singular verbs and pronouns

In American English, a collective noun used as a unit takes singular verbs and pronouns.

To determine the correct verb and pronoun form for a collective noun, you need to consider whether the speaker is referring to the group as a single unit or to the individuals within the group.

When the collective noun is acting as a unit, it is considered singular, and therefore takes a singular verb and pronoun. For example:
- The team is playing well.
- The herd is migrating south for the winter.

In these sentences, "team" and "herd" are both collective nouns, but since they are being treated as a single unit, the singular verb "is" is used.

However, when the emphasis is on the individuals within the group, the collective noun is treated as plural and takes plural verbs and pronouns. For example:
- The team are all wearing their jerseys.
- The herd are grazing in the field.

Here, the focus is on the individual team members and herd animals, so the plural verbs "are" and "are" are used.

It's essential to pay attention to the context and intended meaning of the sentence to determine whether to use a singular or plural verb and pronoun with a collective noun.