Which of the Following Has Been Amplified by China's One-Child

Which of the following has been amplified by China's one-child policy?

A) an unbalanced age ratio with a growing population of younger people and a shrinking elderly population
B) an increase in the number of primary-school students in rural areas of China
C) a larger proportion of males compared to the proportion of females born in China annually
D) an increase in the number of children born annually to couples in which one parent is an only child