Which phrase describes a clause?

a group of adjectives set off from the sentence by commas

a group of words that contains a subject and a verb

a group of words that adds more information to a sentence but can be removed

a group of words that does not express a complete thought

The phrase that describes a clause is "a group of words that contains a subject and a verb."

To determine this, you can break down the options and consider the characteristics of a clause:

- "A group of adjectives set off from the sentence by commas" does not accurately describe a clause. Adjectives typically modify nouns and do not contain a subject and a verb, which are essential components of a clause.

- "A group of words that adds more information to a sentence but can be removed" describes a phrase. Unlike a clause, a phrase does not contain a subject and a verb and cannot express a complete thought. It serves to provide additional information but can be removed from the sentence without altering its grammatical structure.

- "A group of words that does not express a complete thought" also describes a phrase, as mentioned in the previous option. While a clause expresses a complete thought, a phrase does not.

Therefore, the correct answer is "a group of words that contains a subject and a verb" because a clause is a grammatical unit that has a subject (the entity performing the action) and a verb (the action or state of being).