Answer:
Section 2 will decrease.
Step-by-step explanation:
A catalyst is a substance that increases the rate of the chemical reaction without taking part in the overall reaction. Catalysts speed up a reaction by lowering the activation energy needed for a reaction to take place. The activation energy is the minimum energy necessary for a reaction to take place. As such, when a catalyst is added, the activation energy (or the potential energy) needed to start the reaction decreases. This shows itself in the graph by decreasing the "hump" in Section 2.
It should be noted that Sections 1 and 3 will remain the same. This is because the energy of the reactants and products does not change regardless of a catalyst being present.