This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Upper limb, Subject name: Anatomy
[{'content': 'Injury to which of the following nerve leads to the following? \nSelect and explain. \nA. Radial, B. Ulnar, C. Median, D. Posterior interosseus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Wrist drop: may occur due to injury of the radial nerve or paralysis of the extensor muscles of the wrist and hand. In this condition the hand is flexed at the wrist and cannot be extended.', 'role': 'assistant'}]