Harvey's key discovery was that blood circulates how?

• A. The heart pumps blood around the body in a circular motion
• B. Blood circulates from the liver
• C. Blood is produced in the bones
• D. Blood moves only in arteries

Answer: (A)

Blood circulates in a closed loop powered by the heart. Harvey showed that the heart acts as a pump, pushing blood out through the arteries to the body and returning it to the heart through the veins, so the same blood keeps moving in a continuous circuit. This idea means circulation is a circular system, involving both arteries and veins, not just one direction or a source of blood from another organ.

Why the other ideas don’t fit: thinking blood comes from the liver suggests a production site rather than a circulating loop, and blood being produced in bones points to production rather than circulation. Saying blood moves only in arteries ignores the role of veins and the closed loop that makes circulation possible.