In birds,the sound is produced by which of the following?

The given figure shows the human respiratory system with structures labeled $A, B, C,$ and $D$. Which of the following options correctly identifies the structure and its main function or characteristic?

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.

Adam's apple is another name for

The larynx is a modified part of which structure?

Which organ is common to both the digestive and respiratory systems?