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: Unknown
[{'content': "The commonest cause of recurrent shoulder dislocation is - \nSelect and explain. \nA. Shallow glenoid labrum, B. Bankart's lesion, C. The weakness of subscapularis muscle, D. Injury to humeral head", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans-B', 'role': 'assistant'}]