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 :

1. A A is true but R is false
2. B A is false but R is true
3. C Both A and B are true but R is NOT the correct explanation of A Correct answer
4. D Both A and R are true and R is the correct explanation of A