What connects the trachea with the lungs?

The bronchus is the structure that connects the trachea to the lungs. When air is inhaled through the trachea, it travels down into the bronchi, where the trachea bifurcates into the left and right bronchi, directing air into the respective lungs.

In the lungs, the bronchi further divide into smaller branches called bronchioles, leading to the alveoli where gas exchange occurs. The bronchus serves as the primary airway passage, playing a crucial role in the respiratory system by conducting air from the trachea into the lungs.

In contrast, alveoli are tiny air sacs where gas exchange takes place, and the diaphragm is a muscle that aids in inhalation and exhalation but does not directly connect the trachea and lungs. Thus, the bronchus is the correct structure that links the two in the respiratory system.