Which of the following vessels carries oxygenated blood?
A.
Superior vena cava.
B.
Inferior vena cava.
C.
Pulmonary artery.
D.
Pulmonary vein.

The correct answer is:
D. Pulmonary vein.
Explanation:
Superior vena cava (A): Carries deoxygenated blood from the upper part of the body to the right atrium of the heart.
Inferior vena cava (B): Carries deoxygenated blood from the lower part of the body to the right atrium of the heart.
Pulmonary artery (C): Carries deoxygenated blood from the right ventricle of the heart to the lungs.
Pulmonary vein (D): Carries oxygenated blood from the lungs back to the left atrium of the heart.
Therefore, the pulmonary vein is the vessel that carries oxygenated blood.