What is the pH in this problem

Phenylacetic acid (C6H5CH2COOH, or HPAc for short) builds up in the blood of
people with phenylketonuria, an inherited disorder that, if untreated, causes mental
retardation and death. The pKa of HPAc at 25 ºC is 4.32. What is the pH of a 0.25 M
solution of HPAc at 25 ºC?
A. 0.60
B. 2.46
C. 3.12
D. 4.32
E. 5.83
The answer is B, but I don't know why.

pKa= -logKa
Ka=10^-pKa
Ka=4.786*10^-5 very weak acid
C6H5CH2COOH + H2O <---> C6H5CH2COO- + H3O+
0.25M
-X +X +X
0.25-X X X
Ka=[A-][H3O+]/[HPAc]
0.25>>X (Ka very small)
4.786*10^-5=x^2/0.25
x=3.45*10^-3
x=[H3O+]=[H+]
PH=-log[H+]=2.46

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