Calculate the PH of a Buffer That Is 0

Calculate the pH of a buffer that is 0.225 mol L^-1 CH₃COOH and 0.162 mol L^-1 CH₃COOK. The K_a for CH₃COOH is 1.8 × 10^-5.

A) 4.89
B) 9.11
C) 4.74
D) 9.26
E) 4.60