Answer
The pulmonary artery carries oxygen-poor blood.
Work Step by Step
Normally, arteries carry oxygen-rich blood; however, only the pulmonary arteries carry blood that is depleted of oxygen. Arteries, by definition, are blood vessels that carry blood away from the heart. In this case, the pulmonary arteries carry blood away from the heart toward the lungs; this blood has come back from the rest of the body depleted of oxygen and filled with carbon dioxide. The pulmonary arteries carry this blood into the lungs to get rid of the carbon dioxide and fill up with oxygen.
