Which of the following is NOT part of the lower respiratory system?

The pharynx is correctly identified as not being part of the lower respiratory system. It is located in the upper region of the respiratory tract, serving as a passageway for both air and food. The pharynx connects the nasal cavities to the larynx and esophagus, playing a critical role in vocalization and respiration.

In contrast, the alveoli, trachea, and bronchi are all components of the lower respiratory system. The trachea acts as a windpipe, an essential air passage that branches into the bronchi, which lead into the lungs. The alveoli are the tiny air sacs within the lungs where gas exchange occurs, allowing oxygen to enter the bloodstream and carbon dioxide to be expelled. This distinction helps clarify the anatomical structures involved in the respiratory system and their specific functions.