Question

The ________ plays a central role in the circulatory system. It consists of four ________: two for receiving blood and two for pumping blood. A. kidney, veins B. heart, chambers C. heart, veins D. kidney, chambers

Answer 1

B. Heart, Chambers
Heart pumps blood to your body and it has four chambers.
Hope this helps.

Answer 2

The first one is C. heart and the other would be the Heart chambers cause the heart is the one that pumps blood to the body it also has four, Two Atriums and two ventricles 

the Atrium is the upper, the right Atrium receives deoxygenated blood from the veins of the body. as the left Atrium receives oxygenated blood

now the Ventricles each two main chambers of the heart, left and right 
they are what pump the blood one pumps blood in and the other pumps it out.
hope that helps :)