Why is the respiratory system of a bird more efficient than the human respiratory system?
A.A bird lung contains multiple alveoli, which increases the amount of surface area available for gas exchange.
B.The human respiratory system ends in small parabronchi, which reduce the amount of surface area available for gas exchange.
C.The flow-through anatomy of the bird respiratory system does not mix exhaled air with inhaled air.
D.The bird respiratory system consists of a counter-current arrangement of airflow and blood across and through its gill filaments.
E.The internal spaces of the human respiratory system does not provide much surface area for gas exchange.
Answer Key: C