Question

Read the following scenario to answer the following questions.
Blood flowing away from the heart is under tremendous pressure, able to travel to just about any portion of the body. However, blood pressure drops considerably as it moves away from the heart. When blood finally reaches capillaries, the blood pressure drops to nearly zero. Therefore, when a person is standing, blood returning from the feet is not moved back towards the heart by contractions of the heart.
Blood is propelled back to the heart by ________.
A) rhythmic contractions of muscles in the walls of veins and the action of one-way valves
B) skeletal muscle contractions around veins and the action of one-way valves
C) the negative pressure of the heart pulling blood into the empty chambers
D) the natural flow of blood into ever-larger blood vessels leading to the heart

Answer

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