The Nurse Recognizes That the Most Likely Reason a Runner

The nurse recognizes that the most likely reason a runner who has injured his ankle during a race is not aware of it until after he crosses the finish line is that:

A) The emotional exhilaration of running the race masked the pain of the injury
B) His endorphin levels were high as a result of the physical stressors of the race
C) He was mentally distracted by the need to concentrate on the ever-changing nature of the race
D) The physical effects of the injury slowly increased during the race and reached pain-producing capacity only after the race