How is the infinitive phrase used in the sentence?

To wake up on time, set your alarm before going to bed.

A.
adjective

B.
noun as direct object

C.
noun as subject

D.
adverb


Please help!!!

In traditional grammar, it's called an adverbial clause. But nowadays we call it a supplementary adjunct. It's supplementary because it's not integrated tightly into the structure of the main clause, but loosely attached. Notice how it can be discarded without disturbing the grammaticality of the main clause.

PaulM