the smiths have four children and all are girs but the fifth child is a boy.why did this change occur?

a)the law of averages finnaly cathcing up.
b)the fathers contribution to a y chromosome
c)the mothers contribution to a y chromosome
d)the timing of fertelity cycles

3 answers

If a boy was born, it was because he got an X chronosome from mom, and a Y from dad.
so the answr would be c?
Jessica -- as Bobpursley pointed out, boys get the X chromosome from their mothers. C doesn't say that.

Please read your materials over and try again.