In the terminal bronchiole,which of the following is present?

Select the correct option for the trachea.

The nasal cavity and the oral cavity are separated from each other by the:

Select the correct statements about alveoli from the following.
$i$. Air sac of each terminal bronchiole shows $10$ to $12$ alveoli.
$ii$. Each alveolus is surrounded by a network of capillaries.
$iii$. They are lined by ciliated pseudostratified epithelium.
$iv$. They provide surface area for exchange of gases.
$v$. There are about $700$ million alveoli in the lungs.

The largest cartilage of the larynx,which is in the form of a broad ring and is incomplete posteriorly,is:

The structure which prevents the entry of food into the respiratory tract is