Subordination reduces sentences containing less important ideas or facts to

a. independent clauses, dependent clauses, and appositives

b. phrases, appositives, and dependent clauses

I believe the correct answer here is B. Phrases, appositives, and dependent clauses because in Choice A, independent clauses is in the list. An independent clause can act as a sentence, which is the opposite of subordination. Subordination generally creates dependent clauses and appositives, but can sometimes generate phrases.

Probably just give up