A reaction vessel is filled initially with p = 0.50 atm each of SO2, SO3, NO, and NO2. For the reaction at 1000K, KP is equal to 1/9. SO3 (g) + NO (g) → SO2 (g) + NO2 (g) At equilibrium, p(SO3) is: A. 0.111 B. 0.250 C. 0.500 D. 0.750