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': 'Characteristic of benign tumour of lung in x-ray is \nSelect and explain. \nA. Nodule of 3.5 cm, B. Spiculated margin, C. Cavitation, D. Popcorn calcification', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Popcorn or homogenous, concentric, Laminar calcification s/o benign lesion.', 'role': 'assistant'}]