Answer:
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. :)
<span>Long-spined cacti will survive longer and reproduce more often than short-spined cacti</span>. Because natural selection suggests that organisms with certain traits that give them better chance at survival or reproductive rate will be pass on to their offspring.