Answer:
Red blood cells (Ans. 3)
Explanation:
Erythropoietin or EPO is a hormone which is also called as haemopoietin, it is a glycoprotein cytokine. One unique characteristic of hormones is that single hormone helps to apply various effects in different tissues.
For example erythropoietin which is known as traditional circulating hormone is made in the kidney, on the other hand at the same time it produces red blood cells (erythropoiesis) in the bone marrow.