An experiment was carried out to determine whether drinking caffeinated soda increases pulse rate. the pulse rates of 30 year old men and women who were at rest were measured. on day one, each person was given a caffeinated soda. on day two, each person was given caffeine-free soda. one hour after drinking the soda, their 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 dependent variable in this experiment is the (hint: depends on