Q114 , ans : 2
As y chromosome is responsible for male child.X chromosome is not responsible for male child.Since it is spontaneous mutation it can be reversed
@sunitasaxena I am sorry to say that your answer is wrong and the correct answer is option B
The question and answer key is from correct source as it is from kvpy 2014 sx paper
The mutation that occurred is on x-chromosome and is both recessive and lethal since, female is carrier it survives but due to hemizygous condition male is unable to survive.
XXmXX^mXXm → carrier (survives)
XmX^mXmY → dies
While in third generation, the possibility of male child occurs.
May be u r right but in the question it is not mentioned about death of any child.if lethal gene is there .