A track and field coach is trying to decide what beverage is the best pre-training beverage for athletes to drink before a daily training session. The coach has chosen three beverages: a soda, a Gatorade, and water for the athletes to drink before training. The coach will then collect data on their performance during the period of time while training. Afterward, the coach will track the performance of the athletes over an eight week period to see how their performance has changed.
What‘s the independent variable of the experiment?
A. the Training session
B. The types of shoes
C. The athletes being tested
D. The beverages