You are given attributes ABCD and functional dependencies B -> ACD and C -> D as constraints. Also consider a relational database design consisting of a single relation r over R = ABCD.

(a) What are all the keys in ABCD?

(b) Give example of a superkey in ABCD that is not a key.

(c) Give example of a superkey in ABCD that is also a key.

(d) Give example of a trivial functional dependency over ABCD.

(e) Does the design help enforce the dependencies?

(f) Give example of a state of r and a functional dependency that is satisfied by r but does not hold in R.