Blood doping is: Multiple Choice taking stimulants for increased blood circulation adding illegal substances to your blood using other athlete's red blood cell to encourage your body to carry more oxygen removing and freezing a liter of blood and injecting it in before a competition

removing and freezing a liter of blood and injecting it in before a competition

Explanation:

Blood doping is the practice of injecting oxygenated blood into an athlete before a competition in an attempt to enhance athletic performance. The three major ways of blood doping are; blood transfusion of oxygenated blood (frozen blood), injections of erythropoietin, injection of synthetic oxygen carriers.