Erythropoietin is secreted from:: (A) Juxtaglomerular cells, (B) Macula densa, (C) Interstitial cells, (D) Glomerulus
Answer is C. In adults, about  85% of the erythropoietin comes from the kidneys and 15% from the liver. 
Erythropoietin is produced by interstitial cells in the peritubular capillary bed of the kidneys and by perivenous hepatocytes in the liver.