Which of the following statements is true regarding bronchioles?

Bronchioles are indeed part of the conducting zone of the respiratory system. This zone includes structures that transport air to the areas of the lungs involved in gas exchange but do not themselves participate in gas exchange. The conducting zone begins with the trachea and branches into the primary bronchi, secondary bronchi, and continues into the smaller bronchioles.

While bronchioles do not contain cartilage (which is found in larger airways) and do not connect directly to alveoli, they are crucial in regulating airflow and directing air towards the respiratory zone where gas exchange occurs, primarily at the alveolar level. The statement regarding bronchioles being part of the conducting zone accurately reflects their function and organization within the respiratory system, making it the correct choice.

The other options mistakenly attribute characteristics to bronchioles that do not align with their anatomical structure and physiological role. For example, bronchioles lack cartilage; instead, their walls are composed of smooth muscle and elastic fibers, which allow for changes in diameter to regulate airflow.