Which statements describe the action of a catalyst?

I.     It does not alter the \(\Delta H\) for a reaction.

II.     It increases the \({E_{\text{a}}}\) for the reaction.

III.     It alters the mechanism (pathway) of a reaction.

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

B