Which of the following structures would be expected to contain oxygen-rich blood?
I. Pulmonary artery
II. Pulmonary vein
Ill. Superior vena cava

The correct option is B II only

I. Pulmonary artery carries deoxygenated blood from the right ventricle of the heart to the lungs.

II. Pulmonary vein carries oxygenated blood from the lungs to the left atrium of the heart.

III. Superior vena cava collects deoxygenated blood from different parts of the body and carries it to the right atrium of the heart.

So, the correct answer is pulmonary vein i.e. II only.