Determine the [C₂H₃O₂^-] of the Following Solution

Multiple Choice

Determine the [C₂H₃O₂^-] of the following solution. Initial concentrations are given. [HC₂H₃O₂] = 0.250 M, [HI] = 0.120 M [Ka = 1.8 × 10^-5]

A) 8.6 × 10^-6 M
B) 3.8 × 10^-5 M
C) 1.8 × 10^-5 M
D) 0.25 M
E) 0.37 M