Question

Which of the following is a subordinate clause?

Answer 1

I think it is letter C

Answer 2

C.

A subordinate clause begins with a subordinate conjunction or a relative pronoun and will have a subject and a verb. It's not a complete sentence.

The best way to figure out the answer from the choices given is to eliminate answers that are complete sentences. That would get rid of choice A, B, and D. Then you can follow up on that by checking if choice C begins with a subordinate conjunction or a relative pronoun. In the sentence of choice C, "If" is a subordinate conjunction and has a subject and a verb.