Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: When a rod lying freely is heated, no thermal stress is developed in it.
Reason R: On heating, the length of the rod increases In the light of the above statements, choose the correct answer from the options given below:
A. A is true but R is false
B. Both A and R are true and R is the correct explanation of A
C. Both A and R are true but R is NOT the correct explanation of A
D. A is false but R is true