請問如何答

me, her, him, them, us,
anyone of above are right, but in this case, "me" is better, because you got a bread, you must drink something, but just for you, just for this time, no need to bought one carton, so, " us" may be the best answer.
Please note your teacher may be said your answer was wrong if you chose the best one.

the answer is me.

Should be - me.