Heat-labile instruments for use in surgical procedures can be best sterilized by -: (A) Absolute alcohol, (B) Ultraviolet rays, (C) Chlorine releasing compounds, (D) Ethylene oxide gas
Answer is D. “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.