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
[{'content': 'Rideal - walker test is used to compare the efficiency of a disinfectant with that of phenol for the ability to kill \nSelect and explain. \nA. S typhi, B. S paratyphi, C. Pseudomonas, D. E.coli', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Rideal - walker test / phenol coefficient test - abilty to sterilize the suspension of S.typhi.', 'role': 'assistant'}]