Which sentence does NOT contain a subordinate clause? A) Because his sister loved to sing, Don played the piano each evening for her. B) Until all of the students passed the test, the teacher made them work on grammar every day. C) We could see the rain clouds in the distance, but we managed to make it home before the storm. D) Since the students didn't know how to locate their new classrooms, the teachers took all of them on a tour of the new school.