An experiment was carried out to determine whether drinking caffeinated soda increases pulse rate. ● The pulse rates of two groups of people at rest were measured. ● Group A was then given caffeinated soda ● Group B was given caffeine-free soda. ● One hour after drinking the soda, the pulse rates were measured. ● The participants in the experiment were all the same age, and they were all given the same amount of
soda. The control in this experiment is the