Answer:
B) Valves closing
Explanation:
A healthy heart makes a lub-dub sound with each beat. This sound comes from the valves shutting on the blood inside the heart. The first sound (the lub) happens when the mitral and tricuspid valves close.
They are natural pain and stress relievers and with excerise it helps the heart pump blood with less effort.
Exercise, Chew Gum, Participate in events or hang out with friends.
Answer:
volleyball serve. you only need to know how to do that for volleyball and no other sport
Explanation:
