THRZ - Target Heart Rate Zone
It is the level of intensity of cardio during cardio exercise and has different ranges. 60% to 70% ,low intensity this is a warm up for beginners. 70%-80% moderate intensity, it is in this zone that improves body's ability to transport oxygen throughout the body and conditioning one's heart.80% - 90% it in this zone also that allows us to burn more calories.
B. is the answer. hope that helps. :)
It provides water and a way of transportation.
