The only vein that carries oxygenated blood is:Select the correct answer from the code given below:

1. A

   Pulmonary vein

   Pulmonary vein claims to transport oxygenated blood from the lungs directly to the left atrium of the heart. This option is selected as the correct answer because all other major veins carry deoxygenated blood from body tissues, making the pulmonary vein unique in the circulatory system.

2. B

   Cystic vein

   Cystic vein claims to drain deoxygenated blood from the gallbladder. This option is incorrect because it follows the standard pattern of systemic veins carrying deoxygenated blood back toward the heart.

3. C

   Cardiac vein

   Cardiac vein claims to drain deoxygenated blood from the heart muscle itself into the right atrium. This option is incorrect because it does not carry oxygenated blood.

4. D

   Hepatic Portal vein

   Hepatic portal vein claims to carry nutrient-rich deoxygenated blood from the gastrointestinal tract to the liver. This option is incorrect because, despite its unique role in processing nutrients, it transports deoxygenated blood.

Summary. Official key is (a) Pulmonary vein. While standard veins throughout the human body exclusively transport deoxygenated blood towards the heart, the pulmonary veins are an exception as they carry oxygenated blood from the lungs. The cystic, cardiac, and hepatic portal veins all conform to the normal deoxygenated transport pattern. Understanding this distinction is vital for mastering human circulatory physiology. Therefore, option (a) is the only correct choice.