It can be found just above the belly button.
I will choose all because they all are excersices that can keep your pumping.But i think b because that is a lot of excercise witch is goodfor you.for letter B you will have a total of 50 minutes witch is good.
In a study, the independent variable is the thing that you change to see how the change produces different results. In this study, the independent variable would be the use of nicotine.
Answer:
The second option. Increase
