Answer:
C. Exercise three to five days per week.
Step-by-step explanation:
The principle of exercise called "frequency" refers to the number of days you will engage in physical activity to reach your goal. That is, this principle refers to how often you will exercise. This frequency will be determined according to the type of exercise you want to do, your available time, your goals and your fitness. An example of this principle occurs when you decide that the ideal for you is to exercise four to five days a week.
Based on this, we can say that the letter C is the correct answer to your question.