Answer:
A.) Adding more of gas C to the system
Step-by-step explanation:
A.) is correct because the reaction wants to keep the same amount of reactants and products that sustain equilibrium. If you are increasing the amount of gas C, this will push the reaction to make more of the reactants to restore the balance.
B.) is incorrect because heat is a form of energy. As previously stated, when you add more material to the reactants side, the equilibrium shifts to the product side to restore equilibrium.
C.) is incorrect because when the volume is increased, the equilibrium will shift to the side with the greater amount of moles of gas. There is 1 mole of gas on the reactant side (from A (g)) and 3 moles of gas on the products side (from 3 C (g)). Therefore, the reaction will shift to the product side.
D.) is incorrect because if the material on the product side is decreasing, the equilibrium will want to make up that difference by shifting to the product side.
Remember,
reactants ---> products