Answer:
C. the pulmonary artery and vein; they would have to be switched.
Step-by-step explanation:
The pulmonary artery leaves the heart with deoxygenated blood while the pulmonary vein enters the heart with oxygenated blood from the lungs.
The pulmonary artery and pulmonary vein are the only ones that work in the opposite way from the rest of the veins and arteries in the body. The rest of the arteries have oxygenated blood and the rest of the veins have deoxygenated blood.