Which of the following relations is in Boyce-Codd Normal Form (BCNF)?
a. R(ABCD) with FD's: BD -> C ; AB -> D ; AC -> B ; BD -> A
b. R(ABCD) with FD's: BC -> A ; AD -> C ; CD -> B ; BD -> C
c. R(ABCD) with FD's: A -> C ; B -> A ; A -> D ; AD -> C
d. R(ABCD) with FD's: A -> D ; C -> A ; D -> B ; AC -> B
Answer: A