Answer:
Independent variables are ones that can be controlled and dependent variables are results of these changes. So, in question a, an independent variable is amount of a released energy, in these case in form of heat. We reduced that amount and as a result we get a dependent variable as high temperature of chocolate for longer time, so we changed time of a heat releasing from chocolate. In question b, an independent variable is temperature of water, and a dependent variable is amount of produced oxygen. In question c, an independent variable is an intensity of exercise. When we change the intensity of exercise, as a results, breathing rate is changed, which is dependent variable.
Explanation:
