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
Sputum can be disinfected by all of the following methods, EXCEPT: 
Select and explain. 
A. Boiling, B. Autoclaving, C. Cresol, D. Chlorhexidine
D: Chlorhexidine
Answer: D: Chlorhexidine 
Explanation: Sputum can be disinfected using 5% cresol or autoclaving or by boiling. Mycobacterial tuberculosis is resistant to chlorhexidine, acids and alkalies. Of the phenols o-phenylphenol is effective, alcohols, formaldehyde, formaldehyde alcohol, iodine alcohol and ethylene oxide are tuberculocidal agents. Disinfectants commonly used: Faeces and urine: disinfectants used are bleaching powder, formalin, cresol and phenol Room: First wash with soap water Mopping with 5% phenol or 2.5% cresol Spraying of formalin 500ml/1000cu ft Expose to formaldehyde vapor for 24 hours Linen: Boiling, steam disinfection. Exposure formalin gas Dead bodies: 10% formalin or 5% phenol Instruments: 3% Lysol