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: Medicine
[{'content': 'Cubital tunnel syndrome \nSelect and explain. \nA. Radial nerve, B. Ulnar nerve, C. popliteal nerve, D. brachial nerve', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]