In Some Countries Where Boys Are Strongly Preferred Over Girls

In some countries where boys are strongly preferred over girls, there is a significantly higher birth rate of males to females. What does this difference in the birth rate suggest to demographers?

A) These countries may be practicing female infanticide.
B) Women are more likely to choose an abortion if they find out they are carrying girls.
C) Environmental pollution is having an impact on the human body's reproductive system.
D) It suggests nothing, as there are no countries with a significant difference in the birth rate of males to females.