**Core Concept**
Little's area, also known as Kiesselbach's plexus, is a vascular region in the anterior part of the nasal septum. It is a common site of nasal bleeding (epistaxis) due to its rich blood supply from multiple sources. Understanding the contributing arteries is crucial for managing epistaxis.

**Why the Correct Answer is Right**
The posterior ethmoidal artery primarily supplies the posterior part of the nasal septum and lateral nasal wall, rather than the anterior septum. In contrast, the anterior ethmoidal artery, septal branch of the facial artery, and sphenopalatine artery all contribute to Little's area through their anterior nasal septal branches. The posterior ethmoidal artery's branches are more directed towards the posterior nasal cavity, making it less relevant to Little's area.

**Why Each Wrong Option is Incorrect**
**Option A:** The anterior ethmoidal artery is a significant contributor to Little's area, supplying the anterior nasal septum and lateral nasal wall.
**Option B:** The septal branch of the facial artery also contributes to Little's area, providing a rich blood supply to the anterior nasal septum.
**Option C:** The sphenopalatine artery is a major supplier of blood to the nasal cavity, including the anterior nasal septum, and is therefore a contributor to Little's area.

**Clinical Pearl / High-Yield Fact**
Recall that the Little's area is often described as the "triangle of death" due to its high incidence of nasal bleeding. The contributing arteries can be remembered using the mnemonic "ASEP": Anterior ethmoidal, Septal branch of facial, and Sphenopalatine.

**✓ Correct Answer: D. Posterior ethmoidal artery**