Answer:
Kidneys.
Explanation:
Erythropoietin is a hormone that is produced by the kidney and stimulates the production of red blood cells (RBCs) in the bone marrow. Erythropoietin stimulates the bone marrow to generate more RBC's.
By nature, Erythropoietin is a protein with having attached sugar. It is known as the glycoproteins that help in the stimulation for the specific types of RBC's growth in the bone marrow.