Multiple choice Why does the blood in the veins flow only towards heart and not backwards? Because veins have valves. Because the veins are divided into capillaries which are attached to heart. Because the carbon dioxide rich blood tends to flow towards the heart. Because the slope of veins is toward the heart. Reveal answer Fill a bubble to check yourself A Correct answer Explanation Yes, it is correct. The valves present in the veins allow blood to flow only towards the heart.