Which animal possesses a respiratory system where air flows in a single direction through the lungs, allowing continuous renewal of air after each inhalation?

Explanation

Among the listed animals, birds (Aves) have a unique respiratory system characterized by unidirectional airflow through their lungs, ensuring that fresh air is constantly supplied during both inhalation and exhalation. In contrast, cockroaches use a tracheal system, earthworms respire through their skin, and frogs have a bidirectional lung ventilation system.