Cilia line respiratory airways for particle clearance

Steps:

• Identify cilia as hair-like projections that sweep mucus and debris.
• Recall respiratory tract structures use ciliated epithelium to protect lungs.
• Evaluate each option based on anatomical location and function.
• Select the structure in the respiratory system with ciliated lining.

Why B is correct:

• Bronchioles feature pseudostratified ciliated columnar epithelium, which moves mucus to clear inhaled particles, per respiratory physiology.

Why the others are wrong:

• A: Alveoli have simple squamous epithelium for gas diffusion, lacking cilia.
• C: Esophagus is lined with stratified squamous epithelium for protection against abrasion, without cilia.
• D: Small intestine uses simple columnar epithelium with microvilli for absorption, not cilia.

Final answer: B