The correct option is (c).
Explanation
The human circulatory system consists of blood vessels that transport blood throughout the body. The two primary types of blood vessels are arteries and veins, which differ in function, structure, and the type of blood they typically carry.
Statement-wise Analysis
- Statement 1 is Incorrect. Arteries are blood vessels that carry blood away from the heart. In the systemic circulation, arteries carry oxygen-rich blood to various parts of the body. The only exception is the pulmonary artery, which carries carbon dioxide-rich (deoxygenated) blood from the heart to the lungs. Therefore, it is incorrect to state that arteries always carry carbon dioxide-rich blood.
- Statement 2 is Correct. Veins are vessels that collect blood from different parts of the body and bring it back to the heart. Generally, veins carry carbon dioxide-rich (deoxygenated) blood. The exception is the pulmonary vein, which carries oxygen-rich blood from the lungs to the heart. Since the statement uses the qualifier "generally," it accurately reflects the primary function of veins in the systemic circulation.
- Statement 3 is Correct. Blood flows through arteries under high pressure as it is pumped directly by the heart. To withstand this pressure, arteries have thick, elastic walls. In contrast, blood pressure in veins is much lower; therefore, veins have thinner, less elastic walls and possess valves to prevent the backflow of blood.
Key Takeaway
Arteries carry blood away from the heart and typically transport oxygenated blood (except the pulmonary artery) within thick, elastic walls. Veins carry blood toward the heart and typically transport deoxygenated blood (except the pulmonary vein) within thinner walls equipped with valves.