Answer : c
C.K = {A},{CD},{BD}
it's in 1NF :-
it's in 2NF :- every non-prime attribute is fully functionally dependent on each C.K . there is no non-prime attribute on RHS , so it's in 2NF
it's in 3NF :- no non-prime attribute is functionally dependent on non-prime attribute , there is no non-prime attribute on RHS , so, it's in 3NF .
it's not in BCNF :- for BCNF , 3NF must be hold , and another condition is that if a->b then a must be superkey , but in B->C , B is not superkey , it's just prime attribute , (A→BCD , CD→A holds BCNF property) .