Which component ot exercise primarily strengthens your heart

i think it's the first one because doctors aren't the ones who get rid of the old needles. most of them time it's not even doctors who give you shots, it's nurses.

the aorta is the large artery leaving the heart branches into smaller arteries, which eventually branch into capillaries.the arteries carry oxygen and nutrients away from your heart, to your body's tissues. the capillaries are small, thin blood vessels that connect the arteries and the veins. the statement that arteries carry oxygen-rich blood to capillaries is true. veins on the other hand are blood vessels that take oxygen-poor blood back to the heart.