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
Which of the following can be reliably used for hand washing -a) Chlorhexidineb) Isopropyl alcoholc) Lysold) Cresole) Glutaraldehyde 
Select and explain. 
A. ac, B. a, C. ad, D. ab
D: ab
Answer: D: ab 
Explanation: None