Answer: A) Pepsin
Explanation: Acidic solutions are solutions which provide H^+ ions .More is the H^+ ion concentration, more acidic is the solution.
pH of a solution is defined as negative logarithm of H^+ ions concentration.
\(pH =- log{[H^+]}\) or
\(pH = log\frac{1}{[H^+]}\)
Thus lesser is the pH,more is the H^+ concentration and more acidic is the solution.
Thus acidic solutions have low pH and pH ranges from 1 to 7 for acidic solutions.
As can be seen from the graph, enzyme pepsin has highest activity at low pH which means in acidic solutions. As the pH is increasing or the solution is turning basic, the activity of pepsin decreases.
