问题
单项选择题
An overwhelming richness of vegetation may have caused the level of oxygen, to rise above today’s ______ , with a corresponding depletion of carbon dioxide.
A．concentration
B．saturation
C．satiation
D．plenitude
答案
参考答案：A
解析： 名词辨析
A．concentration集中，浓缩，浓度；B．saturation饱和，饱和度；C．satiation饱食，饱满，厌腻；D．plenitude充分；因此A为答案。