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: Pharmacology
[{'content': 'In epidural analgesia morphine acts by acting on - \nSelect and explain. \nA. Substantia gelatinosa, B. Axons, C. Ventral horn, D. Sensory nerve', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Substantia gelatinosa o Analgesic action of morphine has spinal and supraspinal components. It acts in the substantia gelatinosa of dorsal horn to inhibit release of excitatory transmitters from primary afferent carrying pain impulses.", 'role': 'assistant'}]