This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Musculoskeletal Radiology, Subject name: Radiology
[{'content': 'What is the abnormality shown in this shoulder Radiograph? \nSelect and explain. \nA. Anterior Dislocation Of Shoulder, B. Posterior Dislocation Of Shoulder, C. Chondrosarcoma, D. Simple Bone cyst', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Electric Bulb/Light Bulb Appearance on Shoulder Radiograph Is suggestive of posterior Dislocation of Shoulder.', 'role': 'assistant'}]