Olympic Athletes Train in Colorado Springs, Colorado Because This Location

Olympic athletes train in Colorado Springs, Colorado because this location is at high altitude and near the 14,000 foot Pikes Peak. Which statement best describes why this location was chosen?

A) The thin air allows for less resistance when biking or running and, therefore, the athletes can run and bike faster, which builds up their endurance for future races
B) The thinner air causes it to be easier to move into and out of the lungs, which leads to higher oxygen transport.
C) Oxygen levels are low and therefore fewer red blood cells are available, which puts more physiological stress on the body. This leads to a greater efficiency of getting oxygen to the tissues.
D) Oxygen levels are low and, therefore, more red blood cells are produced, giving the athletes an advantage when competing at lower altitudes.
E) The concentration difference for getting air into the lungs is greater at high altitudes.