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': 'Postzone phenomenon is seen in ? \nSelect and explain. \nA. Antigen excess, B. Antibody excess, C. Equivalance zone, D. None of the above', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Antigen excess Postzonc phenomeno - Antigen excessProzone phenomenon - Antibody excess", 'role': 'assistant'}]