A Coach in a large secondary school thinks that ballet training will improve his football teams scoring average/game. He has half of the team members take ballet lessons before the season. The other half of the team does not take such lessons. He then compares mean scoring averages of those with ballet training to those without ballet training:

To test his hypothesis, the Coach should have which of the following groups take ballet training?

a) the best players

b) volunteers

c) the poorest players

d) poorly coordinated players

e) none of the above