Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A) : Gypsum is used for making fireproof wall boards.

Reason (R) : Gypsum is unstable at high temperatures.

In the light of the above statements, choose the correct answer from the options given below :

1. A Both (A) and (R) are correct but (R) is not the correct explanation of (A) Correct answer
2. B Both (A) and (R) are correct and (R) is the correct explanation of (A)
3. C (A) is correct but (R) is not correct
4. D (A) is not correct but (R) is correct