What is an example of a subordinate clause?

A subordinate clause is a group of words that contains a subject and a verb but does not express a complete thought. It cannot stand alone as a sentence and usually starts with a subordinating conjunction, such as "although," "because," or "if." In this case, "Although it was raining" is considered a subordinate clause because it begins with the subordinating conjunction "although." This clause sets the stage for additional information but cannot convey a full idea by itself.

The other choices represent independent clauses, which can function as complete sentences on their own. They express complete thoughts and do not rely on additional information to make sense.