Final answer:
Arteries carry the blood with the highest level of oxygen in the body.
Step-by-step explanation:
The blood vessel where the blood would contain the highest level of oxygen is the arteries. Arteries carry oxygen-rich blood away from the heart and distribute it to tissues throughout the body. Unlike other arteries, the pulmonary artery carries deoxygenated blood from the heart to the lungs to pick up oxygen and release carbon dioxide.