Question

Consider a relation with schema R(A, B, C, D) and FD's BC -> D, D -> A, A -> B. Which of the following is the key of R?

Select one:
a. BD
b. D
c. AB
d. BC

Answer 1

The key of relation R is AB.

Step-by-step explanation:

In order to determine the key of relation R, we need to find the minimal set of attributes that can determine all the other attributes in the relation. To do this, we need to check the closure of each attribute set. Starting with AB, we find that we can determine all attributes in R. Therefore, AB is the key of R.