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': 'Which statement is TRUE regarding pneumothoraxa) Decreased breath soundsb) Decreased percussion notec) Always needs chest tube insertiond) Often needs chest tube insertion \nSelect and explain. \nA. ad, B. c, C. ac, D. ab', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]