Which region of the pharynx is located at the back of the nose?

The nasopharynx is the region located at the back of the nose, serving as the upper part of the pharynx. It connects the nasal cavity to the oropharynx and plays a crucial role in respiratory function. The nasopharynx is responsible for the passage of air during breathing, allowing air to flow from the nasal cavity into the throat. Additionally, it houses the adenoids, which are lymphatic tissue that can help in fighting off infections.

The other regions mentioned serve different functions: the oropharynx is positioned behind the oral cavity and is involved in both respiratory and digestive functions, including swallowing; the laryngopharynx lies beneath the oropharynx and connects to the larynx and esophagus, facilitating the passage of food and air; the term "pharynx" itself refers to the entire structure that includes all these regions, but does not specify any one part, such as where the nasal cavity opens up. Thus, the specificity of the nasopharynx being the area at the back of the nose is what makes it the correct choice.