3. What happens when you breathe in? a. the diaphragm expands and ribcage contracts
b. nothing happen
c. diaphragm explodes and ribcage contracts
d. diaphragm contracts and ribcage expands
4. How does gas exchange happen?
a. take in oxygen and emit carbon dioxide b. take in carbon dioxide and emit oxygen c. inhaling carbon dioxide and exhaling oxygen
d. delivers nutrients needed by the body *​