What is the function of the adverb clause in the sentence?

Since you're getting up early, can you take the dog for a walk in the morning?

It is a dependent clause that acts as a verb.

It answers the question what and modifies the noun dog.

It is a dependent clause that acts as an adjective.

It answers the question why and modifies the verb take.

It answers the question why and modifies the verb take.

Explanation:

Adverb clauses are groups of words consisting of at least a subject and a verb and whose function is to modify or describe adjectives, verbs or other adverbs. They, therefore, provide information about reason, time, place, manner, condition, frequency or degree and are usually introduced by subordinate conjunctions such as since, because, where, when, while, although, after, as, as if, before, so that, unless, even, and until.

The function of the adverb clause in the sentence, which is "Since you're getting up early," is to answer the question "Why" (It provides the reason why the speaker is asking the listener to take the dog for a walk) and to modify the verb "take."

C. It is a dependent clause that acts as an adjective.