Using your heart rate, you can increase the intensity of your workout by:

a: keeping your heart rate at a normal level

b: working to increase your heart rate

c: trying to slow your heart rate down

d: none of the above

B. Working to increase your heart rate

Explanation:

To increase the intensity of your workout, your heart rate needs to work harder so more blood can move through your body

I think according to your question the answer would be b . working to increase your heart rate

b and d are your answers i just answered this question