Which best describes a clause?

A clause is an expression that includes a subject and a predicate, so it performs some sort of action within a sentence.

Explanation:

A clause is the part of a sentence that contains a verb. They also include a subject and a predicate.

a group of words does not have a subject, which performs an action. a group of words that can only serve to modify or describe another part of a sentence. an expression that includes a subject and a predicate, so it performs some sort of action within a sentence.