Blood's double circulation pathway

Steps:

• Blood enters the heart via the vena cava from the body, carrying deoxygenated blood.
• The heart pumps it to the lungs through the pulmonary artery for oxygenation.
• Oxygenated blood returns to the heart via the pulmonary vein.
• The heart then pumps it to the body through the aorta.

Why C is correct:

• It accurately follows the pulmonary circulation definition: deoxygenated blood to lungs via pulmonary artery, then oxygenated back via pulmonary vein, before systemic circulation via aorta.

Why the others are wrong:

• A: Starts with pulmonary vein (oxygenated blood) and incorrectly loops to lungs after aorta.
• B: Omits heart's role after vena cava and misplaces pulmonary artery before lungs.
• D: Reverses pulmonary artery and vein, sending oxygenated blood to lungs incorrectly.

Final answer: C