Between 1990 and 2015, the Poverty Rate in East Asia

Between 1990 and 2015, the poverty rate in East Asia declined dramatically while the poverty rate in sub-Saharan Africa has seen much less of a decline. The main reason for this is that

A) the population growth rate decreased in East Asia and increased in sub-Saharan Africa.
B) Governments in East Asia increased transfer payments to poor families over this period of time. The governments of sub-Saharan Africa had practically no transfer payment programs from 1990 to 2015.
C) The countries of East Asia have progressive income tax systems. The countries of sub-Saharan Africa all have regressive income tax systems.
D) East Asia experienced higher economic growth than sub-Saharan Africa.