Which of the Following Acids Would Serve as a Good

Multiple Choice

Which of the following acids would serve as a good buffer for a reaction at pH = 8.0? $$\begin{array} { l l l } & \mathbf { K } _ { \mathbf { a } } \\\text { I. } & \text { acetic acid } & 1.76 \times 10 - ^ { 5 } \\\text { II. } & \mathrm { H } _ { 2 } \mathrm { PO } _ { 4 } - & 6.31 \times 10 ^ { - 8} \\\text { III. } & \text { bicarbonate } & 5.6 \times 10 ^{- 11 }\\\text { IV. } & \text { TRIS } & 5.01 \times 10 ^ { - 9}\end{array}$$

A) I
B) II
C) III
D) IV