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': 'Antigen binding site in immunoglobulin is \nSelect and explain. \nA. Variable region, B. Hypervariable region, C. Constant region, D. all', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Hypervariable region", 'role': 'assistant'}]