What Has Been an Unintended Consequence of China's One-Child-Per-Couple Policy

What has been an unintended consequence of China's one-child-per-couple policy in terms of the gender ratio in the country?

A) There are equal numbers of men and women.
B) There are many more women than men.
C) The men are much older than the women on average.
D) There are many more men than women.
E) Surprisingly, it made no difference.