Q 49,Paper 2,j14

Let R ={A, B, C, D, E, F} be a relation

schema with the following dependencies

C →F,

E →A,

EC →D,

A →B

Which of the following is a key for R ?

(A) CD (B) EC

(C) AE (D) AC

Answer B.

Explanation.

Ec->EC

Ec-> D

E-> A.and A-> B so E->B.

Ec-> f. AS c->F.

Hence Ec is the key.