We returned it.
Here's why:
* Independent Clause: A complete thought that can stand alone as a sentence.
* Dependent Clause: A clause that cannot stand alone as a sentence and relies on an independent clause for meaning.
In this sentence, "Because shirt had a tear" is a dependent clause. It's a reason, but it doesn't express a complete thought. The independent clause, "We returned it," is the action taken, making it a complete thought.