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': 'Phenol test or Reidel Walker test is done to determine: \nSelect and explain. \nA. Hardness of water, B. Chlorine demand, C. Quality of disinfectant, D. Efficacy of a disinfectants', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. d. Efficacy of a disinfectants', 'role': 'assistant'}]