In a physical education class, 20 students were tested on archery target shooting. These students were then given a two-day training course in archery technique. The students were tested again and showed a 30 percent increase in accuracy. This result proves that the course was effective in increasing peoples target-shooting accuracy. Which of the following, if true, gives the strongest support to the argument above?
A.
The students were all excellent athletes, and excellent athletes tend to be good at target shooting.
B.
The first testing session functioned as a practice session for the second testing session.
C.
The accuracy with which people can shoot arrows is strongly related to the sharpness of their vision.
D.
A similar group of students who were also tested on archery target shooting but were not given the course did not show an increase in accuracy.
E.
Excellence in archery target shooting is an accomplishment achieved by relatively few of the people who take up the sport.