Which words in the sentence are the adverb clause?

Before we leave for our hike, we should put out the camp fire.

Athe camp fire
Bwe should
Cshould put out
Dbefore we leave for our hike

Verified Answer :

An adverb clause is a subordinate clause which cannot exist on its own. Having that in mind, the correct answer is D) before we leave for our hike.