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': 'Following x ray wrist lateral view shows: \nSelect and explain. \nA. Lunate dislocation, B. Perilunate dislocation, C. DISI, D. VISI', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ref. Grainger and Allison's Diagnostic Radiology. Page. 502\n\xa0\nPerilunate dislocation (X ray)\n\nAP radiograph\xa0\n\t\nDislocation is often overlooked\nDisruption of the normally smooth line made by tracing the proximal articular surfaces of the\xa0hamate\xa0and capitate\nIncreased overlap of lunate and capitate\n\n\nLateral radiograph\n\t\nDislocation more easily appreciable\nCapitate not sitting within the distal articular 'cup' of the lunate\nLine drawn through radius and lunate fails to intersect capitate\xa0\nLunate remains in articulation with distal radius (as opposed to lunate dislocation where it is usually in a volar position)\nAbnormal\xa0scapholunate angle\xa0(normal 30-60 degrees, reduced in dorsal perilunate dislocation)\n\n\nAbnormal\xa0capitolunate angle\xa0(normal 0-30 degrees, increased in dorsal perilunate dislocation)", 'role': 'assistant'}]