Help please?
Shontae has been taking her resting heart rate each morning as soon as she wakes up. Over a four month period her resting heart rate has gone from 87 beats per minute to 76 beats per minute. During this same time period Shontae has been actively participating in a cardiovascular fitness program 5 days per week. Which statement most accurately reflects the change in her resting heart rate level?

A) A four month period is not enough time to affect change on the cardiovascular system.
B) A decrease in resting heart rate means her cardiovascular system is working less efficiently.
C) A decrease in resting heart rate means her cardiovascular system is working more efficiently.
D) Her cardiovascular system is showing no effect from the exercise program.