**Core Concept**
Phagocytosis in the central nervous system (CNS) is a critical process for removing pathogens, dead cells, and debris. This process is primarily carried out by specific cell types within the CNS. The **microglia** are key players in this process, acting as the resident immune cells of the brain.

**Why the Correct Answer is Right**
The correct answer is related to the role of **microglia** in the CNS. Microglia are highly motile and dynamically survey their surroundings, allowing them to rapidly respond to injury or infection by transforming into an active, phagocytic state. They express a range of receptors that enable them to recognize and engulf foreign particles, dead cells, and other materials.

**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because while **astrocytes** play a crucial role in maintaining the CNS environment, including providing support to neurons and contributing to the blood-brain barrier, they are not the primary phagocytic cells.
**Option B:** This choice is incorrect as **oligodendrocytes** are responsible for myelinating neuronal axons in the CNS but are not involved in phagocytosis.
**Option D:** This choice is incorrect because **neurons** are the primary functional units of the nervous system, responsible for transmitting information, and do not have a significant role in phagocytosis.

**Clinical Pearl / High-Yield Fact**
It's crucial to remember that **microglia** are not only involved in phagocytosis but also play a significant role in neuroinflammatory processes and the pathogenesis of neurodegenerative diseases.

**Correct Answer:** D. Microglia