Substance X is converted to substance Y in a chemical reaction. What role would a catalyst play in this scenario?

Question

A.
It would increase the solubility of substance X into the solvent needed to speed up the reaction.

B.
It would speed up the reaction by becoming part of the products.

C.
It would increase the pH in order to dissolve substance X to make the reaction happen.

D.
It would speed up the reaction without changing or becoming part of the produc