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
[{'content': 'Pasteurised milk is most commonly tested by \nSelect and explain. \nA. Phosphate test, B. Coliform test, C. Catalase test, D. Oxidase test', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Phosphatase test:This is a check on whether milk has been pasteurized. The enzyme phosphatase, which is normally present in milk, is inactivated if pasteurization has been performed properly. Residual phosphatase activity indicates that pasteurization has been adequate. This test, if positive after proper pasteurization of milk shows contamination after pasteurization. (Ref: Ananthanarayan 9th edition, p631-632)', 'role': 'assistant'}]