This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Renal physiology, Subject name: Physiology
[{'content': 'Relaxation of mesangial cells is caused by \nSelect and explain. \nA. Histamine, B. Dopamine, C. Angiotension 2, D. Vasopressin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Dopamine causes relaxation of mesangial cells. Other three are agents causing contraction.Ref: Ganong&;s Review of Medical Physiology, 23rd edition, page no: 646', 'role': 'assistant'}]