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': "Which of the following is not a Koch's postulate? \nSelect and explain. \nA. The bacteria should be able to be isolated from a diseased tissue, B. When inoculated in experimental animals, bacteria may or may not cause disease, C. Pure cultures can be obtained, D. Bacteria should be able to be isolated from the diseased tissue in the experimental animals", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]