I think it’s subordinate since it can’t stand on its own. Subordinates add more information to the sentence.
I think the answer is B, because she is trying to please Edmund and therefore gives him the food he requests.
C. Education beyond high school versus education beyond college because in the other examples you can't really use those topics because there isn't really much about them, but in example C. you can tell the two similarities in both the high school and college, and you could put there differences. Hope I helped!