Which type of pronoun is used in the following sentence? Mars, which is sometimes called the Red Planet, is the fourth planet in the solar system. A. indefinite B. demonstrative C. interrogative D. relative

The sentence contains a D. relative pronoun.

A relative pronoun introduces dependent or relative clauses. The most common relative pronouns are who, whom, whose, which, and that.

The relative pronoun in the sentence is "which"; it connects the dependent clause to the proper noun, "Mars."