Which statement about respiratory epithelium is true?

• A. It is non-ciliated and avascular.
• B. Goblet cells are absent.
• C. It contains keratinized surfaces.
• D. It contains ciliated cells and goblet cells for mucociliary clearance.

Answer: (D)

Respiratory epithelium is specialized for removing inhaled debris through mucociliary clearance. It features ciliated cells that beat in a coordinated way and goblet cells that secrete mucus. The mucus traps dust, microbes, and other particles, and the cilia propel this mucus upward toward the pharynx to be swallowed or coughed out. This combination—ciliated cells plus goblet cells for mucus production—provides the essential mechanism of clearing the airway surface.

That’s why the statement describing both ciliated cells and goblet cells for mucociliary clearance is correct. The other options don’t fit: the epithelium is not non-ciliated, goblet cells are present, and respiratory mucosa is not keratinized.