23. The reaction system has already reached equilibrium. Which of the following statements is correct? (A) Additional H2O(g) added to the system will shift to the left to obtain the equilibrium. (B) As an exothermic reaction, the system will shift to the right to attain the equilibrium when temperature increases. (C) When carbon dioxide is removed, the system will shift to the left to achieve the equilibrium. (D) When volume of the reaction container is decreased, the system will shift to the right to reach the equilibrium. (E) Addition of helium gas into the reaction system will have no effects on its equilibrium.