Where does oxygen finally reach from the lungs?

The figure shows a diagrammatic view of the human respiratory system with labels $A, B, C$,and $D$. Select the option which gives the correct identification and main function and/or characteristic.

The outer pleural membrane is in close contact with the .....

The alveolar sac of the lungs and the villi of the intestine have a similar function,which is that:

Alveolar surfactant is

Identify which respiratory structure possesses the following features and choose the correct option accordingly.
$I.$ Found in mammals
$II.$ Highly muscular and fibrous partition,elevated towards the thorax like a dome
$III.$ Separates thoracic and abdominal cavity