Consider the Equilibrium Reaction a Sample of Pure NO₂(g)

Consider the equilibrium reaction A sample of pure NO₂(g) of concentration 0.140 M is allowed to come to equilibrium. It is then found that 57.0 % of the NO₂(g) has reacted to form N₂O₄(g) . What is the value of K_c?

A) 0.211
B) 0.377
C) 0.754
D) 4.73
E) 11.0