Hi zuotengdazuo,
There is a slight difference between answers A & B if you analyse carefully.
If I say that your work is TO BE DONE, it means we are expecting the completion in the near future. However, at the present moment, it is not fully done.
If I say work is BEING DONE, it means you are in the midst of finishing.
Which is closer to your goal? To be admitted or being admitted? If I were a student, being admitted makes me happier because I am closer to my goal if I am "being admitted" as compared to "to be admitted".
I hope I have shed some light for you.
Cheers, Lance