How Does Taking a Drug Like Erythropoietin (EPO) Benefit an Athlete

How does taking a drug like erythropoietin (EPO) benefit an athlete?

A) Since EPO thickens the blood, it forces the heart to work harder. At the time of competition, the heart is then stronger and more efficient at delivering oxygen to the athlete's muscle cells.
B) Since EPO increases the ability of mitochondria to make ATP in the absence of oxygen, muscle cells can produce energy even when the athlete is out of breath.
C) Since EPO binds to cholesterol and removes it from the body, it cleans the blood vessels. Clear blood vessels mean better blood flow and delivery of oxygen.
D) Since EPO increases the number of red blood cells, it increases the amount of oxygen the athlete's blood can carry, and this gives the athlete greater endurance.