I dont agree with B and rather would go with D
Choice B assumes that even when the couple has one son , they still keep giving bith to more babies. That may not be true.
Also in B,
How is that possible ?? B assumes that population rate will reduce when the couple uses birth-control measures after the birth of their first son. That means that the male population will be reduced .
In all , this is a pretty crazy question. there are lot of possibilities here.
More Insights...