The intensity of an activity refers to the a. length of time it takes for an exercise or group of exercises to be complete. b. number of times an exercise or group of exercises is performed within an certain time frame. c. amount of energy exerted while performing an exercise. d. classification of exercise.

The correct answer is: C. amount of energy exerted while performing an exercise. 
This answer choice makes the most sense. More energy makes an exercise more intense.

Well if you pick a machine to work on and that's gonna be your exercise if you don't stick to that machine your muscle strength your muscle mass rather will change because you haven't been doing it you change something in your exercise routine which changes your body's form of dealing with things for example you might become weaker or stronger depending on what kind of exercises you do in whether or not the machine you picked actually your muscles grow.

The administration should take action.