**Core Concept**
The nasal mucosa, being a complex mucosal surface, receives its blood supply from multiple sources to meet its high metabolic demands. This includes branches from both the internal and external carotid arteries to ensure a rich and constant blood supply.

**Why the Correct Answer is Right**
The nasal mucosa is primarily supplied by the **sphenopalatine artery**, which is a branch of the **maxillary artery** (a terminal branch of the external carotid artery). The sphenopalatine artery is responsible for supplying the majority of the nasal mucosa, including the turbinate bones, septum, and lateral walls of the nasal cavity. This rich blood supply is essential for the mucosa's role in humidification, filtration, and olfaction.

**Why Each Wrong Option is Incorrect**
* **Option A:** The **facial artery** is a branch of the external carotid artery, but it primarily supplies the face, including the nasal ala and tip, rather than the nasal mucosa.
* **Option B:** The **ophthalmic artery**, a branch of the internal carotid artery, supplies the eye and surrounding structures, but not the nasal mucosa.
* **Option C:** The **superior and inferior labial arteries** are branches of the facial artery and supply the lips and surrounding tissues, not the nasal mucosa.

**Clinical Pearl / High-Yield Fact**
In patients with nasal trauma or epistaxis (nosebleeds), the sphenopalatine artery is a common source of bleeding due to its rich blood supply and proximity to the nasal septum.

**Correct Answer: A. Sphenopalatine artery**