Answer:
D. airway. lungs. muscles.
It's D. Stretching opens up arteries. This makes blood more able to get through and lowers blood pressure. Stretching makes your muscles ready for an exercise. Improved circulation is just like lowering blood pressure because it opens up arteries, veins, and capillaries. D is wrong because stretching doesn't make your heart stronger. I hope this helps! :)
C. Delivers more oxygen to the body
