Hydrogen Iodide Decomposes According to the Equation 2HI(g) $\rightleftharpoons$ H₂(g) + I₂(g), for Which K_c = 0

Hydrogen iodide decomposes according to the equation 2HI(g) $\rightleftharpoons$ H₂(g) + I₂(g) , for which K_c = 0.0156 at 400ºC. 0.550 mol HI was injected into a 2.00 L reaction vessel at 400ºC. Calculate the concentration of HI at equilibrium.

A) 0.138 M
B) 0.220 M
C) 0.550 M
D) 0.275 M
E) 0.0275 M