Answer: True.
Explanation: If your resting heart rate has decreased since the beginning of the semester, this means that it takes less strength from your heart to pump the blood throughout your body. When your heart isn't working as hard, and it has the availability to get stronger. Thus your heart's beats per minute will decrease.
Example: If you are working out intensely for several days without taking a day to rest, this won't be good for your muscles because they'll hardly have anytime to heal and strengthen themselves. When you don't workout every single day, your muscles will have time to grow in size and strength.