The respiratory system is derived from which germ layer?

Alveolus of lungs is lined by . . . . . . .

The epithelium in the bronchioles is

$A$ pair of small lymphatic tissue present at the sides of the root of the tongue is called as:

Alveolar surfactant is

'$XX$' is a part of the respiratory system that contains $C$-shaped rings of hyaline cartilage. '$XX$' is lined with ciliated,pseudostratified columnar epithelium. Identify '$XX$'.