Vessels Entering the Heart Atria

Steps:

• Recall heart anatomy: atria receive incoming blood before ventricles.
• Right atrium gets deoxygenated blood from superior/inferior vena cavae (label 2).
• Left atrium gets oxygenated blood from pulmonary veins (label 4).
• Confirm: only these veins deliver directly to atria; arteries exit ventricles.

Why D is correct:

• Vena cavae (2) drain systemic blood into right atrium; pulmonary veins (4) drain lung blood into left atrium, per standard cardiac circulation.

Why the others are wrong:

• A: Includes 1 (aorta), which exits left ventricle to body, not entering atria.
• B: Includes 1 (aorta) and 3 (pulmonary artery), both carrying blood out from ventricles.
• C: Includes 3 (pulmonary artery), which delivers deoxygenated blood from right ventricle to lungs.

Final answer: D