Question

what is the best tool to use to set fitness goals and measure intensity during interval running?
wearable step tracker
heart rate monitor
stopwatch
tape measure

Explanation:

A heart rate monitor can measure the intensity of exercise by tracking heart - rate, which is a key indicator of exercise intensity. It can also help set fitness goals related to target heart - rate zones. A step tracker mainly counts steps, a stopwatch measures time, and a tape measure is for length measurements.

Answer:

B. heart rate monitor