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: Surgery
[{'content': 'In a case of tuberculosis of the thoracic spine, the earliest sign of cord compression is: \nSelect and explain. \nA. Bladder dysfunction, B. Extensor plantar, C. Motor weakness, D. Sensory loss', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. b. Extensor plantar', 'role': 'assistant'}]