Why did China relax its "one-child" policy in 2015 and 'two child policy' in 2021 per family?

a. The Chinese government is very concerned about female infanticide.
b. The country is worried about future labor shortages.
c. The Chinese government is very concerned about the inability of Chinese males to find wives.
d. The Chinese government wants to overpopulate the planet. e. China needs more females.