Which could be the catalyst in a chemical reaction? OA reactants
O B. product
OC. enzyme
OD. activated complex

 C. enzyme

Explanation:

A catalyst is a substance which increases the rate of a reaction by taking the reaction through a different path which involves lower activation energy and thus more molecules can cross the energy barrier and convert to products.

The catalyst itself does not take part in the chemical reaction and is regenerated as such at the end.

Enzymes are proteins that reduce the activation energy of biological reaction. Enzymes increase the speed of a reaction and help it to run faster. Thus they are also called as bio catalysts.

Activated complex is the transition state which is very unstable and is formed during the course when reactants are converted to products.

the answer is 75.0%.