For the Following Reaction, the Equilibrium Constant Kc Is 2

For the following reaction, the equilibrium constant Kc is 2.0 at a certain temperature. If the concentration of both products is 0.10 M at equilibrium, what is the concentration of the starting material, NOBr?
2NOBr(g) ⇌ 2NO(g) + Br2(g)

A) 5 × 10-4 M
B) 2.2 × 10-4 M
C) 5 × 10-2 M
D) 2.2 × 10-2 M
E) 2.2 M