Question

the respiratory membrane consists of:
a the walls of the alveoli and mucous membrane.
b the walls of the alveoli and capillaries.
c pulmonary capillary beds.
d walls of bronchioles and alveoli.

Explanation:

The respiratory membrane is where gas - exchange occurs. It is composed of the walls of the alveoli and the walls of the capillaries surrounding them. This thin membrane allows for the diffusion of oxygen and carbon dioxide between the air in the alveoli and the blood in the capillaries.

Answer:

B. the walls of the alveoli and capillaries.