5. which of the following statements is true of a scientific theory? a. it's an accepted explanation for how the world works. b. it explains what happens but not how it happens. c. it's a guess accepted by a few scientists. d. it's been proven incorrect

energy and particles

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.