血浆的pH主要决定于下述哪个缓冲对

A、K_{2<\/sub>HPO4<\/sub>\/KH2<\/sub>PO4<\/sub>
B、KHCO3<\/sub>\/H2<\/sub>CO3<\/sub>
C、NaHCO3<\/sub>\/H2<\/sub>CO3<\/sub>
D、Na2<\/sub>HPO4<\/sub>\/NaH2<\/sub>PO4<\/sub>
E、蛋白质-Na\/蛋白质}