This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Heat labile instruments for use in surgical procedures can be best sterilized by: 
Select and explain. 
A. Absolute alcohol, B. Ultra violet rays, C. Chlorine releasing compounds, D. Ethylene oxide gas
D: Ethylene oxide gas
Answer: D: Ethylene oxide gas 
Explanation: Ethylene oxide gas is used in hospitals for the sterilization of heat-sensitive materials such as surgical instruments and plastics. It kills by alkylating both proteins and nucleic acids (i.e., the hydroxyethyl group attacks the reactive hydrogen atoms on essential amino and hydroxyl groups). Note - Ethylene oxide is an effective sterilizing agent for heat-labile devices such as aificial hea valves that cannot be treated at the temperature of the autoclave. Ref: Ray C.G., Ryan K.J. (2010). Chapter 3. Sterilization, Disinfection, and Infection Control. In C.G. Ray, K.J. Ryan (Eds), Sherris Medical Microbiology, 5e