Question

During aerobic activity, if your heart rate is lower than the lower limit, you are ___________________.

not pushing yourself hard enough

pushing yourself to the limit

at just the right spot

pushing yourself too hard

Answer 1

Not pushing yourself hard enough is the answer since your heart rate doesn't even hit your lower minimum.
Pushing yourself to the limit is at your max heart rate.
Just at the right spot is at your max heart rate.
Pushing yourself too hard is above your max heart rate.