For the reaction $CO_{(g)} + H_2O_{(g)} \rightleftharpoons CO_{2(g)} + H_{2(g)}$,the equilibrium amount of $CO_{2(g)}$ increases by:

• A
  Adding a suitable catalyst
• B
  Adding an inert gas
• C
  Decreasing the volume of the container
• D
  Increasing the amount of $CO_{(g)}$