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. Ultraviolet rays, C. Chlorine releasing compounds, D. Ethylene oxide gas
D: Ethylene oxide gas
Answer: D: Ethylene oxide gas 
Explanation: “Ethylene oxide used mainly by industry for the sterilization of plastic and other thermolabile material that cannot withstand heating" - Greenwood 16th /ep. 74.

Other methods for sterilization of heat labile instruments

- Ionizing radiation
- Formaldehyde in combination with subatmospheric steam.