單項選擇題(2007)各物質(zhì)濃度均為0.10mol/dm3的下列水溶液中,其pH最小的是:[已知(NH3)=1.77×10-5,(CH3COOH)=1.76×10-5]()

A.NH4Cl
B.NH3
C.CH3COOH
D.CH3COOH+CH3COONa