The pulmonary circuit is the only route in which arteries carry less oxygen than veins. a. true b. false

The answer is a, true. 

Usually, in arteries, the main function is to carry oxygenated blood and the blood with nutrients away from the heart to other organs for them to function. And veins, which carries deoxygenated blood and blood with waste materials from other organs back to the heart. 

The only exception is for the pulmonary artery and vein. Pulmonary artery does carry blood away from the heart too, but it carries the deoxygenated blood that is used earlier back to the lungs for gas exchange. And after the gas exchange in lungs, where the blood would be filled with oxygen and waste are carried away, those blood would be transferred back to the heart through the pulmonary vein. 

So, the answer should be true.