What happens to rib muscles and the diaphragm when you
inhale and hold your breath?

When you breathe in, or inhale, your diaphragm contracts and moves downward. This increases the space in your chest cavity, and your lungs expand into it. The muscles between your ribs also help enlarge the chest cavity. They contract to pull your rib cage both upward and outward when you inhale.

Explanation:

i think the answer would be b.