Bronchi contain cartilage, ciliated epithelium, and smooth muscle

Steps:

• Bronchi are conducting airways in the respiratory system requiring structural support, mucus clearance, and airflow regulation.
• Cartilage provides rigidity to prevent collapse during breathing.
• Ciliated pseudostratified epithelium lines the lumen to trap and move particles upward.
• Smooth muscle layers allow bronchoconstriction and dilation for ventilation control.

Why A is correct:

• Respiratory anatomy defines bronchi as having incomplete hyaline cartilage rings, ciliated columnar epithelium, and circumferential smooth muscle.

Why the others are wrong:

• B: Smooth muscle is present to regulate airway diameter.
• C: Both cartilage and ciliated epithelium are essential for support and protection in bronchi.
• D: Cartilage rings are present to maintain bronchial patency.

Final answer: A