Identify the A and B and then mark the correct statement.

Step-by-step solution

A is vein and B is artery. Pulmonary vein carries oxygenated blood from lungs to heart. Blood vessels contain three linings (not layers)- Tunica externa, tunica media and tunica intima. Lumen is more in veins as it has thin tunica media. The blood flows strictly by a fixed route through Blood Vessels-the arteries and veins. Basically, each artery and vein consists of three layers: an inner lining of squamous endothelium, the tunica intima, a middle layer of smooth muscle and elastic fibres, the tunica media, and an