Assertion : Normally monospermy occurs in most of animals .
Reason : Vitelline membrane of ovum checks polyspermy .

Options

A. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
C. If the assertion is true but the reason is false
D. If both the assertion and reason are false

Answer

B

Explanation

Monospermy is found in most of animals. As the sperm head comes in the contact with the fertilization cone it causes opening of + Na channel to cause depolarization of ovum membrane (fast block to check polyspermy). Moreover critical granules beneath egg plasma membrane make the zona pellucida impervious to second sperm by destroying sperm receptors.