I think all of them are right.

As we can see B can't be derived from any FDs, therefore, it will surely be a prime attribute.

Now we can take B closure; since B alone can't derive anything therefore we will make pairs as:

[BA]^{+ } = BACD (as BA->C and C->D)

since we got all attributes here, therefore, AB is Candidate key.

[BD]^{+ } = BDAC (as D->A and AB->C)

since we got all attributes here, therefore, BD is Candidate key.

[BC]^{+ } = BCDA (as C->D and D->A)

since we got all attributes here therefore, BC is Candidate key.