Answer: Option A
Step-by-step explanation:
EPO is erythropoietin is produced and released into the blood from the kidneys in case where there is inadequate oxygen supply. EPO is carried to the bone marrow where it triggers the production of red blood cells.
In case the athletes takes EPO from outside to increase the efficiency of work, will decrease the production of EPO naturally from the kidney.
This is because the athlete is taking EPO from outside for performance increase.