Distinguishing artery and vein structures by wall composition

Steps:

• Arteries have thick walls with elastic fibers and smooth muscle to withstand pressure; veins have thinner walls with more collagen.
• Inner lining of blood vessels is endothelium, a simple squamous epithelium specialized for blood contact.
• Label 1 identifies the thick-walled vessel as artery; label 2 the thin-walled as vein.
• Labels 3-5 match collagen in outer layer, smooth muscle for contraction, and endothelium lining.

Why B is correct:

• Arteries contain elastic and collagen fibers plus thick smooth muscle (per vascular histology); endothelium is the precise term for the tunica intima lining.

Why the others are wrong:

• A: Misnames vessels as specific (aorta, vena cava) and uses "epithelium" instead of endothelium.
• C: Swaps artery/vein labels and incorrectly calls lining "squamous epithelium" without specifying endothelium.
• D: Specifies coronary vessels unnecessarily and errs with "squamous cells epithelium" over endothelium.

Final answer: B