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: Radiology
[{'content': 'Which of the following is gold standard for the diagnosis of minimal bronchiectasis \nSelect and explain. \nA. Bronchography, B. Plain CT scan, C. X-ray chest, D. CT scan with contrast', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Plain CT scan', 'role': 'assistant'}]