Final answer:
The air travels through the following components of the respiratory tract: Trachea, Bronchi, Bronchioles, and finally reaches the Alveoli, where gas exchange takes place. Option a is correct.
Step-by-step explanation:
The correct order of structures that air passes through from generation 0 (the mouth and nose) to generation 23 (the alveoli) is: Trachea, Bronchi, Bronchioles, Alveoli. Initially, when we breathe in, air enters through the nasal cavity and then moves to the larynx, after which it enters the trachea.
The trachea bifurcates into the left and right bronchi, which further divide into smaller bronchioles. These continue to branch and get progressively smaller until ending in the alveoli, where gas exchange takes place. Each alveolar duct culminates in alveolar sacs, which house the alveoli.
The large surface area of alveoli, combined with their thin walls, facilitates the diffusion of oxygen into the blood and carbon dioxide out of the blood, which is then exhaled. This exchange is critical to our respiratory and circulatory systems, providing oxygen to our body while removing waste gases.