Which of the Following Solutions Is a Good Buffer System

Multiple Choice

Which of the following solutions is a good buffer system?

A) a solution that is 0.10 mol L^-1 NaCl and 0.10 mol L^-1 HCl
B) a solution that is 0.10 mol L^-1 HCN and 0.10 mol L^-1 LiCN
C) a solution that is 0.10 mol L^-1 NaOH and 0.10 mol L^-1 HNO₃
D) a solution that is 0.10 mol L^-1 HNO₃ and 0.10 mol L^-1 KNO₃
E) a solution that is 0.10 mol L^-1 HCN and 0.10 mol L^-1 NaCl