The liver stores excess iron in ferritin.

A. Superior and inferior venae cavae:The venae cavae carry deoxygenated blood from the body into the right atrium, not toward the lungs. They are part of systemic venous return, not pulmonary circulation.

B. Aorta and pulmonary arteries:The aorta carries oxygenated blood from the left ventricle to the body, so it does not transport blood to the lungs. Only the pulmonary arteries are involved in carrying blood toward the lungs.

C. Pulmonary trunk and veins:The pulmonary veins carry oxygenated blood from the lungs to the left atrium, which is away from the lungs. Only the pulmonary trunk directs blood toward the lungs.

D. Pulmonary arteries and veins:While the pulmonary arteries carry deoxygenated blood to the lungs, the pulmonary veins return oxygenated blood to the heart. Only arteries carry blood toward the lungs.

E. Pulmonary trunk and arteries:The pulmonary trunk originates from the right ventricle and branches into the left and right pulmonary arteries, which transport deoxygenated blood to the lungs for oxygenation. This makes them the correct structures for carrying blood toward the lungs.

The liver plays a central role in iron metabolism by storing excess iron in the protein ferritin. Ferritin safely binds iron, preventing it from catalyzing harmful free radical reactions, and releases it when the body needs it for processes such as hemoglobin synthesis. This storage mechanism helps maintain iron homeostasis and prevents iron deficiency or overload.