What are human trachea epithelium specialized to do

To moisten and to protect the airway from stuff like unknown pathogens and infection

Explanation:

The Trachea also known as the windpipe has tons of 'little hairs' called cilia in the epithelium that protect the throat. When someone smokes or breathes in gases it is destroyed and exposes the trachea. But thats another story. :)

the correct answer is d