I am no expert but I think the correct answer is C.
Answer;
Oxygen or an oxidizing agent to receive electrons must be present for oxidation to occur in chemical reactions.
Explanation;
Oxidation entails the loss of electrons from these molecules, causing them to become unstable and highly reactive and leading to their eventual reaction with and damage of cell components such as membranes.
-In redox reaction; The ion or molecule that accepts electrons is called the oxidizing agent; by accepting electrons it causes the oxidation of another species. Conversely, the species that donates electrons is called the reducing agent; when the reaction occurs, it reduces the other species.
I think the correct answer from the choices listed above is the second option. The enzyme pepsin that is present in the stomach denature in the intestine due to the alkaline environment of the intestine. This is because pepsin has an optimum pH that is very low which is ideal for the acidic conditions of the stomach.
