The cardiovascular system performs four main functions: first, of the heart generate blood pressure, which moves blood through the .

*second, the blood vessels blood from the heart into arteries, capillaries, and veins. then, blood returns to the heart to complete the .

*third, gas occurs in the capillaries, where oxygen is dropped off for the cells, and coâ‚‚ and wastes are picked up.

*finally, the heart and blood vessels blood flow, according to the needs of the body.

•The cardiovascular system performs four main functions: first, contraction of the heart generates blood pressure, which moves blood through the blood vessels.

Blood pressure is the pressure generated by the heart pumping in circulating blood on the walls of blood vessels.  

•Second, the blood vessels transport blood from the heart into arteries, capillaries, and veins. Then, blood returns to the heart to complete the circuit.

This is an example of system circuit where oxygenated blood from the heart’s left ventricle through the aorta and to the rest of the body and then oxygen-poor blood from all tissues is then returned through the veins back to heart.

•Third, gas exchange occurs in the capillaries, where oxygen is dropped off for the cells, and CO2‚ and wastes are picked up.

During this gas exchange, cells take oxygen from the blood for their function and release their metabolic waste. Deoxygenated blood goes to the heart and then to the lungs for more oxygen.

•Finally, the heart and blood vessels regulate blood flow, according to the needs of the body.

Blood flow is regulated via smooth muscles that are located in the blood vessels. Smooth muscles can contract and relax, consequently constrict and dilate vessels.This is directed by nerve and hormone signals.

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.

is this a psat question, if so do not cheat try your best.