Assertion (A): In the absence of fertilisation menstruation occurs. Reason (R): The corpus luteum degenerates. This causes disintegration of the endometrium leading to menstruation. Regarding (A) and (R):

Question

( A ) A is incorrect but R is correct
( B ) A is correct but R is incorrect
( C ) Both A and R are correct & R is the correct explanation for A
( D ) Both A and R are correct but R is not the correct explanation for A