This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hematopoeisis: Basic concepts, Subject name: Pathology
[{'content': 'Erythropoetin in fetus is secreted by? \nSelect and explain. \nA. Liver, B. Marrow, C. Spleen, D. Kidney', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Sources of erythropoietin: Fetus: Liver Adult: Interstitial cells in peritubular capillary bed of kidneys (85%). Perivenous hepatocytes in the liver (15%). Brain (protective effect against excitotoxic damage triggered by hypoxia).', 'role': 'assistant'}]