Which of the following is altered by a catalyst?

A. difference between the energies of products and reactants

B. average kinetic energy of products

C. average kinetic energy of reactants

D. activation energy

In chemistry, a catalyst can speed up the reaction (or make it initiate easier) by altering the activation energy, lowering it enough to allow the reactants to react more easily. Some negative catalysts or inhibitors can do the same by increasing the activation energy.