Assertion (A) : A step - up transformer cannot be used as a step- down transformer.
Reason (R) : A transformer work only in one direction.

Options

A. Both (A) & (R ) are true and (R ) is correct explanation of (A )
B. Both (A) & (R ) are true , and (R ) is not correct explanation of (A )
C. (A ) is true , but (R ) is false
D. (A) is false and (R ) is also false