Which pair of compounds could be used to make a buffer solution (assuming appropriate molar ratios)?

A.     KCl and HCl

B.     NaCl and HCl

C.     \({\text{KHS}}{{\text{O}}_{\text{4}}}\) and \({{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}\)

D.     \({\text{C}}{{\text{H}}_{\text{3}}}{\text{COONa}}\) and \({\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH}}\)

D