Answer for 25 points also I’ll mark you as the brainiest ! For the quickest answer.

Answer:
The Fourth Point (between 4 and 5)
You find the optimal pH by looking for the pH with the highest activity.
Explanation:
The optimal ph is basically where the enzyme has THE MOST activity.
The fourth point of the pH, and activity is the optimal pH because it has the most activity out of the nine points.