Mammalian lungs have enormous number of minute alveoli (air sacs). It is to allow

Options

A. More space for increasing the volume of inspired air
B. More surface area for diffusion of gases
C. More spongy texture for keeping lungs in proper shape
D. More nerve supply to keep organs active when working

Answer

B

Explanation

Alveoli are tiny sacs within our lungs that allow oxygen and carbon dioxide to move between lungs and blooodstream. They increase surface area for diffusion of gases.