Tracheal cartilage maintains airway structure

Steps:

• Identify trachea as a flexible tube reinforced to stay open during breathing.
• Recall C-shaped hyaline cartilage rings provide rigidity without full encirclement for flexibility.
• Match function to label: tissue preventing collapse is supportive cartilage.
• Confirm A labels the cartilage in the diagram.

Why A is correct:

• Hyaline cartilage rings in the trachea provide structural support, preventing collapse under pressure changes during respiration (standard anatomical definition).

Why the others are wrong:

• B: Epithelium lines the inner surface for protection and mucociliary clearance, not structural rigidity.
• C: Smooth muscle controls airway diameter but lacks strength to prevent collapse.
• D: Glands secrete mucus for lubrication, offering no mechanical support.

Final answer: A