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: Physiology
[{'content': 'Substance P is increased is response to pain in periphery, by which of the following? \nSelect and explain. \nA. Mast cells, B. Endothelium, C. Plasma, D. Nerve terminals', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Substance P\xa0seen at\n\nPrimary pain nerve endings in dorsal horn of spinal cord\nHypothalamus\nNigrostrial pathway of basal ganglia', 'role': 'assistant'}]