The gender imbalance in China's under-20 population, with fewer females, is attributed to:

• A. Sex-selective abortion
• B. Higher female mortality
• C. Female infanticide
• D. Migration of females

Answer: (C)

The key idea here is how cultural preferences shape who survives into the younger ages. In parts of China, a strong preference for sons led families to treat newborn girls as less desirable. When girl infants were not nurtured or were killed, the number of females who make it into the under-20 age group drops relative to males. This direct reduction in female survival creates a noticeable gender imbalance in the younger population.

While sex-selective abortion can also reduce the number of girls, its effect is most immediately seen at birth, whereas infanticide directly lowers female survival after birth, producing the skew in the under-20 cohort that this question highlights. Higher female mortality and migration into or out of the country can influence gender ratios too, but the most straightforward and historically documented mechanism that produces a deficit of females among those under twenty is female infanticide driven by son preference.