This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Breast, Subject name: Surgery
[{'content': 'Winging of scapula is seen after mastectomy due to injury: \nSelect and explain. \nA. Musculocutaneous nerve, B. Long thoracic nerve of Bell, C. Intercostobrachial nerve, D. Thoracodorsal nerve', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Winging of scapula is seen after mastectomy due to injury of long thoracic nerve .', 'role': 'assistant'}]