The correct answer is A. Arteries.
Arteries are blood vessels that carry oxygen-rich blood away from the heart to the rest of the body. They are thick-walled and muscular, which helps them to maintain a high blood pressure. This high blood pressure is necessary to ensure that blood is pumped all the way to the smallest blood vessels, the capillaries, where it can deliver oxygen and nutrients to the tissues.
Veins are blood vessels that carry oxygen-poor blood from the body back to the heart. They are thin-walled and have valves that help to prevent blood from flowing backwards.
Muscle fibers are the basic units of muscle tissue. They are long, thin cells that can contract and relax, which allows them to move the body.
Nerves are the body’s communication system. They carry messages from the brain and spinal cord to the rest of the body, and from the body back to the brain and spinal cord.
I hope this helps!