Trivia: What vessels carry oxygen-poor blood back to the heart?
Lymph nodes
Veins
Carotid arteries
Small intestine
The correct answer is Veins
So why is this answer correct? : Veins carry oxygen-poor blood — which is the blood that has already been used by your other organs — back to your heart. Nearly 75% of the blood in your body is held in veins, which can have a blue appearance underneath the skin. This is an optical illusion because of how light hits the skin; your blood is still red even if it is deoxygenated.