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': 'In tabes dorsalis demyelination occurs in all areas, EXCEPT: \nSelect and explain. \nA. Posterior column, B. Posterior root, C. Posterior root ganglion, D. Basal ganglia', 'role': 'user'}, {'content': "Answer: D \nExplanation: Tabes dorsalis Late manifestation of syphilis Symptoms and signs of demyelination of the posterior columns, dorsal roots, and dorsal root ganglia. Symptoms are Ataxic wide-based gait Foot drop Paresthesia; Bladder disturbances; Impotence; Areflexia; and Loss of positional, Deep-pain, and Temperature sensations. Trophic joint degeneration (Charcot's joints) can result from loss of pain sensation. Optic atrophy occurs in tabes. Ref: Harrison, E-18, P-1383", 'role': 'assistant'}]