Q.

Assertion: The sex of the children will be determined by chromosome received from the father.
Reason: A human male has one-X and one Y-chromosome.

1 Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.  
2 Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.  
3 Assertion is true but Reason is false.  
4 Assertion is false but Reason is true.  

Ans.

(1)

If a child inherits X-chromosome from the father it will be a girl and one who inherits a Y-chromosome will be a boy. Thus, both assertion and reason are correct and reason is the correct explanation of assertion.