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: Medicine
[{'content': 'Immune tolerance can be induced by- \nSelect and explain. \nA. Excess antigen, B. Excess antibody, C. Excess complement level, D. Neonatal thymectomy', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]