**Core Concept**
The posterior cerebral artery (PCA) is a crucial branch of the Circle of Willis, supplying blood to the occipital lobe, thalamus, and parts of the temporal lobe. It plays a vital role in maintaining visual and sensory functions.

**Why the Correct Answer is Right**
The PCA arises from the basilar artery, which is formed by the fusion of the two vertebral arteries. The basilar artery then bifurcates into the two PCA branches, supplying the posterior aspect of the brain. This branching pattern is essential for maintaining blood flow to the visual cortex and other critical brain regions. The PCA's origin from the basilar artery is a fundamental anatomical fact that is often tested in medical exams.

**Why Each Wrong Option is Incorrect**
* **Option A:** The internal carotid artery primarily supplies the anterior aspect of the brain, including the frontal, parietal, and temporal lobes. It does not give rise to the PCA.
* **Option B:** The middle cerebral artery is another branch of the internal carotid artery, but it is involved in supplying the lateral surface of the hemisphere, not the posterior aspect.
* **Option D:** The anterior cerebral artery is also a branch of the internal carotid artery, primarily supplying the medial aspect of the hemisphere, not the PCA territory.

**Clinical Pearl / High-Yield Fact**
The PCA's origin from the basilar artery is a key anatomical detail that is often tested in medical exams. Remembering this fact can help you answer questions related to the Circle of Willis and the cerebral vasculature.

**Correct Answer:** C. Basilar artery.