Determine the correctness (or otherwise) of the following Assertion [A] and the Reason [R]

Q. Determine the correctness (or otherwise) of the following Assertion [A] and the Reason [R]

Assertion [A]: For a material exhibiting Coble creep, a reduction in grain size results in a significant increase in creep rate

Reason [R]: Grain boundaries act as a barrier to motion of dislocations

A. Both [A] and [R] are true and [R] is the correct reason for [A]

B. Both [A] and [R] are true, but [R] is not the correct reason for [A]

C. Both [A] and [R] are false

D. [A] is true but [R] is false

Ans: Both [A] and [R] are true, but [R] is not the correct reason for [A]