【名词&注释】
污染源(pollution source)、饮用水(drinking water)、样本代表性(representatives of samples)、分层抽样(stratified sampling)、脾肾阳虚(yang deficiency of spleen and kidney)、规律性、密切相关(closely related)、抽样误差(sampling error)、肾阳虚衰(deficiency of the kidney-yang)、蛋白质营养价值(protein nutritive value)
[单选题]与泄泻发病密切相关(closely related)的内因为( )
A. 肾阳虚衰(deficiency of the kidney-yang)
B. 脾胃虚弱
C. 肝脾不和
D. 脾肾阳虚
E. 心肾不交