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
Erythropoietin is/are produced by - 
Select and explain. 
A. Juxtaglomerular cells, B. Interstitial cells of the peritubular capillary bed of the kidneys, C. Pars recta of PCT, D. Macula densa
B: Interstitial cells of the peritubular capillary bed of the kidneys
Answer: B: Interstitial cells of the peritubular capillary bed of the kidneys 
Explanation: Ans. B. Interstitial cells of the peritubular capillary bed of the kidneysErythropoietin is a glycoprotein hormone which stimulate erythrocyte production.In adults, about 85% of erythropoietin comes from the kidney (interstitial cells in peritubular capillary bed) and 15% from liver (Perivenous hepatocytes). Small amount is also produced in brain; and uterus and oviduct.