Ptyalin is present in human saliva, is a metalloenzyme and requires calcium ions for function. The optimum conditions for ptyalin activity are a pH range of 5.6–6.9, a temperature of 37°C, and the presence of certain anions and activators, such as chloride, bromide, and iodide. Pepsin is most active in acidic environments between 37 °C and 42 °C. Accordingly, its primary site of synthesis and activity is in the stomach (pH 1.5 to 2). Pepsin exhibits maximal activity at pH 2.0 and is inactive at pH 6.5 and above, however pepsin is not fully denatured or irreversibly inactivated until pH 8.0. Trypsis optimum pH is 7.8-8.7. Thus, option B is correct.