Answer:
Wrist and chest Monitor
Explanation:
The wrist and Chest Monitor would be the most useful in determining whether you are staying within your target heart rate zone during a workout because during workout or any kind of activity to get the heart rate of an individual it is mostly gotten from the chest and wrist of the individual.
Calorimeter is used to measure the amount of calories in the body or the amount of calories burnt during workout of the individual while the wrist and chest monitor measures the heart rate.
