Question: 154 Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Endometrium is necessary for implantation of blastocyst.
Reason R: In the absence of fertilization, the corpus luteum degenerates that causes disintegration of endometrium.
In the light of the above statements, choose the correct answer from the options given below:
(1) \mathbf{A} is true but \mathbf{R} is false.
(2) \mathbf{A} is false but \mathbf{R} is true.
(3) Both \mathbf{A} and \mathbf{R} are true and \mathbf{R} is the correct explanation of \mathbf{A}.
(4) Both \mathbf{A} and \mathbf{R} are true but \mathbf{R} is NOT the correct explanation of \mathbf{A}.
Answer: Option (4)
Explanation:
The endometrium is the inner lining of the uterus and provides the site for implantation of the blastocyst, so Assertion A is true.
In the absence of fertilization, the corpus luteum degenerates, leading to a decrease in progesterone level,
which causes shedding or disintegration of the endometrium, so Reason R is also true.
However, Reason R explains the cause of menstruation when fertilization does not occur and does not
explain why the endometrium is necessary for implantation.
Therefore, both statements are true but Reason R is not the correct explanation of Assertion A.