This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidneys and Body Fluids, 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 kidneys(Ref. Ganong25th edp.701)Major source of erythropoietin is Interstitial cells of the peritubular capillary bed of the kidneys