As a good friend of his, I offered Tom my congratulations ______ his passing the college entrance exams.

1. A.
   at
2. B.
   on
3. C.
   for
4. D.
   of

As a good friend of his, I offered Tom my congratulations ______ his passing the college entrance exams.                         

  A. at                             B. on                                  C. for                                D. of    

As a good friend of his, I offered Tom my congratulations ______ his passing the college entrance exams.