They need energy to produce oxygen
In the given case, there is a need to ensure that the exercise is very well monitored. However, in my opinion, the most essential characteristic he requires to change is the people. First of all, all the subjects are of a school sports team, therefore, they all would be fit, and they are all about the same age group.
Thus, the results would vary if the level of fitness, the age of teenagers, and sex differ. It is thus, essential to record the outcomes from a wide array of individuals in order to reduce the bias of the experimental design in the given case. Therefore, testing additional boys as well as several girls from different classes would be appropriate in the given case.
They are the basic unit of matter
