根据IPAT方程，若某地区未来特定时期内人口规模和人均GDP都翻倍，则单位GDP的环境负荷应（ ）变化才能维持环境负荷不变 According to the IPAT equation, if both the population size and GDP per capita double in a given region, then the environmental load per unit of GDP should （ ）in order to keep the environmental impacts unchanged
A、同期内增长到原来的4倍 Increase by four times in the same period
B、同期内增长到原来的2倍 Increase by 2 times in the same period
C、同期内降低到原来的1/4 Drop to the original 1/4 in the same period
D、同期内降低到原来的1/2 Drop to the original 1/2 in the same period