Answer:
C) Using a heart rate monitor
Step-by-step explanation:
A heart rate monitor is used to measure the heartbeat during physical activity. Thus, it is a powerful tool for controlling exercise intensity (as intensity increases heart rate) and ensuring training safety. This handset consists of two components. One is a band that surrounds the chest and detects the electronic pulses generated by the heartbeat. The other is a watch that receives signals from the chest strap. Depending on the model, the device displays, in addition to heart rate, other information such as calorie expenditure and oxygen consumption.