For the Equilibrium PCl₅(g) $\rightleftharpoons$ PCl₃(g) + Cl₂(g), K_c = 4

For the equilibrium PCl₅(g) $\rightleftharpoons$ PCl₃(g) + Cl₂(g) , K_c = 4.0 at 228°C. If pure PCl₅ is placed in a 1.00-L container and allowed to come to equilibrium, and the equilibrium concentration of PCl₅(g) is 0.19 M, what is the equilibrium concentration of PCl₃?

A) 0.095 M
B) 0.4 M
C) 0.19 M
D) 0.87 M
E) 0.009 M