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': 'Cause of death which is common in case of coma \nSelect and explain. \nA. Tongue falling back and obstructing airway, B. Secretions obstructing airway, C. Cardiac arrest, D. Epilepsy', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]