I believe there is more than one answer to this question. B is the only answer that is an independent clause. A, C, and D are all dependent clauses, so presumably they are all answers. They are dependent because they cannot stand alone as a sentence without an independent clause. Hope that helped you.
Well i had a friend who was really cocky and selfish, she only thought about herself most of the time thus making her actions reckless and dumb due to her doing stuff only for herself.