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': 'Restrosternal tumor cause - \nSelect and explain. \nA. Bluish discolouration of the face, B. Edema of face, C. can occur in thyroid tumors, D. All', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]