The frequency of an activity refers to the A. Length of time it takes for an exercise or group of exercises to be complete

B. classification of exercise

C. amount of energy exerted while performing and exercise

D. number of times an exercise or group of exercises is performed Within certain amount of time frame

The answer would be "D" Because the definition of frequency is the number of times you do something in a certain amount of time.

Explanation:

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delegated (sometimes called enumerated or expressed) powers are specifically granted to the federal government in article i, section 8 of the constitution. this includes the power to coin money, to regulate commerce, to declare war, to raise and maintain armed forces, and to establish a post office.