This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S, 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: In medicine, pronator drift refers to a pathologic sign seen during a neurological examination. Jean Alexandre Barre is credited with having first described it; thus it is sometimes known as the Barre test or sign. A positive result indicates spasticity seen in UMN lesion of upper limb Ref Harrison20th edition pg 2345', 'role': 'assistant'}]