AB is the key here which determines C ,D E there is no P.D and T.D between C,D,E SO IT IS IN 3NF
Now for BCNF every determinant is a candidate key determinant here are A,B,C (as C determines B) but C is not candidate key hence it is not in BCNF (only if C->B is removed it becomes BCNF)
AC is also key which can determine B and so also D , E but B is not candidate key
hence ans is C