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: Physiology
[{'content': 'Sodium channels are specifically blocked by ? \nSelect and explain. \nA. Nifedipine, B. Tetra Ethyl lead, C. Tetradotoxin, D. Choline', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. Tetradotoxin', 'role': 'assistant'}]