Which statement about all living organisms is true?
A. They have limbs.
B. They produce their own food.
C. They breathe air.
D. They have at least one cell.

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.