Which of the Following Acids (Listed with PK_a Values) and Its

Which of the following acids (listed with pK_a values) and its conjugate would be the best choice to make a buffer with a pH of 2.12?

A) HC₇H₅O₂, pK_a = 4.19
B) CH₃COOH, pK_a = 4.74
C) HClO, pK_a = 7.54
D) HCN, pK_a = 9.31
E) HClO₂, pK_a = 1.96