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': 'Most common nutritional deficiency seen after gastrectomy \nSelect and explain. \nA. Iron deficiency, B. B12 deficiency, C. Vitamin d deficiency, D. Vitamin k deficiency', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Most common complication is violin deficiency.', 'role': 'assistant'}]