Which of the following statements is true for a catalyst?

• A
  $A$ catalyst increases the rate of reaction by lowering the activation energy.
• B
  $A$ catalyst does not participate in the reaction mechanism.
• C
  If $\Delta G$ is more negative,it can be said that the catalyst speeds up the reaction.
• D
  $A$ catalyst shifts the equilibrium constant of the reaction in favor of the forward reaction.