Division of mammalian lungs into a very large number of tiny alveoli around alveolar ducts opening into brondchioles, is

Options

A. an inefficient system of ventilation of alveoli throug with very little residual air in the lungs
B. an inefficient system of ventilation of alveoli resuting in very high precentage of residual air in the lungs
C. a very efficient system of ventilation of alveoli with no resdiual air in the lungs
D. an efficient system of ventilation of alveoli with little or no residual in the lungs.

Answer

D