I don’t have CourseHero, but I did find this Prezi that looks like it has the information you need: https://prezi.com/2xx4atwhjhno/traitor-and-patriot-chart-of-brutus-and-caesar/
I believe the answer is B
The conclusion
explanation- i learned that before
Subordinate clauses are often used because they (B) add variety to the sentence structure. They are not complete thoughts and can function only when linked to an independent clause.