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: Surgery
[{'content': 'Dysphagia lusoria is diagnosed by \nSelect and explain. \nA. Barium swallow, B. Endoscopy, C. CT angiography, D. PET CT', 'role': 'user'}, {'content': 'Answer: C \nExplanation: It is aberrant right subclavian artery pressing on the oesophagus causing dysphagia. Diagnosed by CT angiography.', 'role': 'assistant'}]