This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
[{'content': 'Most heat sensitive vaccine \nSelect and explain. \nA. BCG, B. TT, C. OPV, D. Small pox', 'role': 'user'}, {'content': 'Answer: C \nExplanation: According to heat sensitivity of vaccines ,they are arranged in to 6 groups ie Group A to Group F Most heat sensitive are in group A and least in Group F OPV is included in group A Reference; Park&;s Textbook of Preventive and Social medicine; 24th edition; Page no. 114', 'role': 'assistant'}]