The food chain is a system in which food is connected with the ecosystem. Ex:composers, producers, decomposers,etc.
Answer: Pulmonary artery
Explanation:
All arteries carry blood away from the heart while all veins carry blood to the heart. With the exception of pulmonary artery, all arteries contain oxygenated blood while all veins except pulmonary vein contain deoxygenated blood.
Thus, pulmonary artery is the answer