Aqueous solutions of `HNO_(3), KOH, CH_(3)COOH`,and `CH_(3)COONa` of identical concentrations are provided. The pair (s) of solution which form a buffer upon mixing is// are
A. `HNO_(3)` and `CH_(3)COOH`
B. `KOH` and `CH_(3)COONa`
C. `HNO_(3)` and `CH_(3)COONa`
D. `CH_(3)COOH` and `CH_(3)COONa`