This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Lung, Subject name: Surgery
[{'content': 'Bronchiolithiasis means \nSelect and explain. \nA. Calcified lymph nodes eroding into bronchus, B. Foreign body calcified in bronchus, C. Lithium deposition in bronchial wall, D. A hamartoma', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans: a (Calcified lymph nodes eroding into bronchus)Ref: Dorland's 28thed, p. 231", 'role': 'assistant'}]