Question

catalysts increase the rate of a reaction by
a being consumed during the reaction.
b raising the temperature of the reaction.
c raising the concentration of the reactants.
d lowering the activation energy of a reaction.

Explanation:

Catalysts are substances that speed up chemical reactions without being consumed. They work by providing an alternative reaction pathway with a lower activation energy. Changing temperature (B) or reactant concentration (C) are other factors affecting reaction rate but not how catalysts function. Catalysts are not consumed during the reaction (A).

Answer:

D. lowering the activation energy of a reaction