The correct answer is C) Just because she and Gretchen are rivals does not mean they can't be friends. Because in the end, they look at each other and smile, the way people who could get along do.
I'd say it's D) Indirect object, but I'm not sure, so don't take my word as gospel :)
Mastering has experiments and always getting them right
A. It is the only one that has the person himself speaking