Consider the Following Reaction

Consider the following reaction:
POCl₃(g) ⇌ POCl(g) + Cl₂(g) with K_c = 0.450
A sample of pure POCl₃(g) was placed in a reaction vessel and allowed to decompose according to the above reaction.At equilibrium,the concentrations of POCl(g) and Cl₂(g) were each 0.150 M.What was the initial concentration of POCl₃(g) ?

A) 0.225 M
B) 0.200 M
C) 0.633 M
D) 0.483 M
E) 0.350 M