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
All the following agents can be used as skin disinfectants, except 
Select and explain. 
A. Chloroxylenol, B. Tincture iodine, C. Quaternary ammonium compounds, D. Isopropyl alcohol
C: Quaternary ammonium compounds
Answer: C: Quaternary ammonium compounds 
Explanation: Chloroxylenol - Phenol. Tincture iodine - Halogen, Isopropyl alcohol - Alcohol Ref : Ananthanarayana textbook of Microbiology 9th edition Pgno : 33