What prevents backflow of blood inside the heart during contraction?
(a) Valves in heart
(b) Thick muscular walls of ventricles
(c) Thin walls of atria
(d) All of the above
Valves ensure there is no backflow of blood inside the heart during contraction they close and separate oxygenated and deoxygenated blood from mixing.
Thick muscular walls of ventricles have to pump blood out of the heart.
Thin walls of atria carry the blood towards the heart.
Hence option (a) is correct.