Which of the following structures is the entry point for air into the lungs?

The entry point for air into the lungs is the trachea. The trachea, also known as the windpipe, serves as the main airway through which air travels from the throat down into the lungs. It branches into the bronchi, which then lead directly into each lung, where further branching occurs into smaller airways and ultimately into the alveoli, where gas exchange takes place.

While bronchi are important in directing air into the lungs after it passes through the trachea, they do not serve as the primary entry point. The larynx, often referred to as the voice box, is located above the trachea and plays a role in voice production and protecting the airway during swallowing, but it is not the main entry point for air. Alveoli are the tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide occurs, and they are not involved in the initial entry of air but rather in the final stages of respiration.