This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Medicine
[{'content': 'Activation of the renin stimulates - \nSelect and explain. \nA. Water excretion, B. Potassium retention, C. Sodium retention, D. Magnesium excretion', 'role': 'user'}, {'content': 'Answer: C \nExplanation: increase secretion of renin causes sodium retention, potassium excretion, increase ECF volume, magnesium retention ( Harrison 17 pg 2251)', 'role': 'assistant'}]