C it's for because you said my brother is writing an essay blank the graduation party so ill before because he is riding it for a graduation party he's doing it for a graduation party cuz if it was in order to be my brother is writing an essay in order to the graduation party it doesn't make sense if it was to my brother is writing an essay to the graduation party no ill before because he's doing it for the graduation party is writing it for the graduation party so it makes more sense