Question

activities
1 hour of napping
1 hour of watching television
1 hour of walking on a treadmill
a student measures her heart rate after each of the activities listed. based on this information, which is a constant in the students investigation?
equipment needed for activity
length of activity time
activity performed
energy expended during activity

Explanation:

The student measures heart - rate after activities. Each activity is 1 hour long. The equipment varies (no equipment for napping, TV for watching TV, treadmill for walking), the activities are different (napping, watching TV, walking), and energy expended will differ. But the length of time for each activity is always 1 hour.

Answer:

B. length of activity time