Identify the term that best describes the italicized words. we left the auditorium before the concert was over. noun clause

Well, this really depends on the word or words that are italicized. However, I did find somewhere on the Internet that the italicized words are before the concert was over.
If that is the case, then the correct answer is adverbial clause, given that it functions as a simple adverb, that is, it answers the question - when did something happen?
When did we leave the auditorium? - Before the concert was over.

Pretty sure the answer is C. Indefinite Adjective

Explanation:

this is a word used to describe a noun (person, place, or thing). The adjective here is indefinite, it does not describe in detail. etc.. that girl (what girl?) that house(what house?)