The graph below illustrates the relationship between enzyme activity and pH for catalase, peptidase, and cellulase. Based on the graph, which of the following optimal pH is correct?

• A. Catalase, pH 7.0
• B. Peptidase, pH 5.5
• C. Cellulase, pH 6.5
• D. Peptidase, pH 8.0

Answer: (A)