In alveoli of the lungs the air at the site of gas exchange is separted from the blood by

Options

A. alveolar epithelium only
B. alveolar epithelium and capillary endothelium
C. alveolar epithelium capillary endothelium and tunica adventitia
D. alveloar epithelium capillary endothelium a thin layer of tunica media and tunica adventitia

Answer

B

Explanation

The wall of the capillaries consistes of only tunica internate which is made u[ of simple squamous endothelium The wall of alveloi is also very thin consisting of squamous epithelium