Marina is trying to pay more attention to her health, and she has been monitoring her heart rate using a fitness tracker. Yesterday, she got into her first-choice college. When she checked her tracker, she noticed that her heart rate was higher for most of the afternoon. What BEST explains this?
A. Strong emotions can impact the heart rate. B. She probably exercised and forgot about it.
C. If she was sitting most of the afternoon, it would be high.
D. Heart rates are unpredictable and don't generally follow patterns.​