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': 'Pronator drip is a sign of - \nSelect and explain. \nA. UMN lesion of upper limb, B. LMN lesion, C. Dorsal syringomyelia, D. Carpel tunnel syndrome', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]