This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: general microbiology, Subject name: Microbiology
Operation theatres are sterilized by? 
Select and explain. 
A. Carbolic acid spraying, B. Washing with soap and water, C. Formaldehyde, D. ETO gas
C: Formaldehyde
Answer: C: Formaldehyde 
Explanation: FORMALDEHYDE GAS is used for sterilizing instruments and heat sensitive catheters and for fumigating wards, sick rooms, and laboratories REF:Ananthanarayan and Panicker's Textbook ofMicrobiology 8thEdition pg no:36