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': 'True about left sided colon carcinoma - \nSelect and explain. \nA. Anemia, B. Obstruction, C. Melena, D. Feculant vomiting', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]