Which of the parent birds shown above (a or b) appears to have greater fitness? Explain your answer.

a. by using fur or clothes to trap heat energy near the body

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.