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: Dental
All of the following can be used for sterilization of hand piece except: 
Select and explain. 
A. Autoclave, B. Chemical vapour sterilization, C. ETOX, D. Dry heat sterilization
D: Dry heat sterilization
Answer: D: Dry heat sterilization 
Explanation: Autoclave sterilization of hand pieces is one of the most rapid methods of sterilization. However, fibre optics dim with repeated heat sterilization in several months to a year, apparently owing to oil residue and debris baked on the ends of the optical fibres.
Chemical vapour sterilization is recommended for some types of hand pieces- apparently works well with ceramic -bearing hand pieces.
ETOX (ethylene oxide) gas is the greatest method of sterilization used for hand pieces.
Dry heat sterilization of hand pieces is generally not recommended.