Before Oscar Pistorius received a ticket to the London Olympics, the IAAF banned prosthetics from participating in the Olympics. The reason is: Leopard blade prosthetics are strong, low-density and strong, and can rebound 97% of energy when running Therefore, the wearer runs faster and faster, and the rear speed is beyond the reach of normal people. If the following are true, the reasons for least supporting the IAAF are:. ['it is the responsibility of the IAAF to create opportunities for fair competition.', 'Existing sports laws do not restrict prosthetics to participate in the Olympics.', 'Leopard blade prosthetics are expensive and ordinary people cannot afford them.', 'Leopard blade prostheses do not cure body defects.']