1. [A] valves in heart You must know that in human beings, valves in heart, ensure that blood does not flow backwards, when the atria or ventricles contract. Hence, your answer will be option [A].

    [A] valves in heart
    You must know that in human beings, valves in heart, ensure that blood does not flow backwards, when the atria or ventricles contract. Hence, your answer will be option [A].

    See less
    • 1