Which of the following sentences is correct?
a. a phrase has a subject and verb, but a clause does not.
b. a clause has a subject and verb, but a phrase does not.
c. a clause is a group of related words, but a phrase is not.
d. a phrase is a group of related words, but a clause is not.

B. A clause has a subject and a verb, but a phrase does not.

In Grammar, a clause is a set of words (that are related to each other) that contains a subject and its corresponding verb. A clause by itself is a group of words, that express a complete idea. Clauses usually are short, simple sentences. Whereas a phrase doesn't have both a subject and a verb. Hence, clauses are a group of words, that could state ideas independently, as separate sentences having a subject and predicate.

Explanation:

a. the scene is structured as a dialogue between two characters in their own informal language.