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': 'Oblitration of left cardiac shadow on PA view is due to: \nSelect and explain. \nA. Lingular lesion, B. Left hilar lymphadenopathy, C. Left lower lobe lesion, D. Left upper apical lobe lesion', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Lingular lesion', 'role': 'assistant'}]