The activation energy of a reaction can be lowered by the addition of a:Group of answer choicesCatalystProductSubstrateCofactor

The activation energy of a reaction can be lowered by the addition of a Catalyst.

Step by Step Explanation:

1. The activation energy is the minimum amount of energy required to start a chemical reaction. It's like the initial push needed to start a reaction.

2. A catalyst is a substance that can increase the rate of a reaction by lowering the activation energy, but is not consumed in the reaction itself.

3. When a catalyst is added to the reaction, it provides an alternative reaction pathway with a lower activation energy.

4. This allows more reactant particles to have enough energy to reach the activation energy, thus increasing the rate of reaction.

5. Therefore, the correct answer is Catalyst.

Products, substrates, and cofactors do not have the ability to lower the activation energy of a reaction. Products are the end result of a reaction, substrates are the starting materials in enzymatic reactions, and cofactors are non-protein chemical compounds that are required for a protein's biological activity, but none of these can lower the activation energy like a catalyst can.