Solutions Are Made by Combining Equal Amounts of the Following

Solutions are made by combining equal amounts of the following. Which is a buffer?

A) 0.1 M HCl + 0.1 M Cl ^-
B) 0.1 M HF + 0.1 M Na⁺
C) 0.1 M HF + 0.1 M NaOH
D) 0.1 M NaF + 0.05 M HF
E) 0.1 M NaF + 0.05 M Na⁺