Final answer:
The correct answer is e. Both A and C are true because all statements are correct; steam under pressure is the mechanism, and the steam both heats and wets the objects. After cooling, microorganisms are destroyed.
Step-by-step explanation:
The autoclave process involves moist-heat sterilization, which is effective in sterilizing objects such as surgical equipment. The main mechanism of action in an autoclave is steam under pressure, which allows the steam to reach temperatures above the boiling point of water and effectively kill microorganisms, including endospores that are resistant to boiling temperatures. The steam both heats and wets the objects, ensuring they come into direct contact with the high temperature. Items must be loosely wrapped to allow steam penetration and, after the cycle is complete and the chamber has cooled, the microorganisms on the objects are destroyed.
Given this information, the correct answer to the student's question is e. Both A and C are true. As all statements provided are correct, statement a. 'All of the above are true' is indeed accurate, just as statements b. and d. describe correct aspects of the autoclave process. However, since 'All of the above are true' encompasses both the mechanism of action and the steam's simultaneous heating and wetting, option e. encompasses the completeness of option a. Therefore, e. is the most comprehensive answer.