Why would a school implement the Healthier US School Challenge?

to make kids more motivated to change what they eat on a daily basis with an incentive

i believe the answer would be 'd'.

hope this !

the more fit you are, the faster the recovery. your heart rate drops most sharply in the first minute after you stop exercising; it should then fall about 20 beats a minute—a drop of less than 12 beats a minute is considered abnormal. this “recovery heart rate” is measured as part of an exercise stress test.