**Core Concept**
Meningioma is a type of slow-growing, typically benign tumor that arises from the meninges, the protective membranes surrounding the brain and spinal cord. These tumors are often categorized as low-grade, indicating a lower likelihood of aggressive behavior and metastasis.

**Why the Correct Answer is Right**
Meningioma is characterized by its slow growth and generally favorable prognosis, with a tendency to be encapsulated and well-circumscribed. The tumor's behavior is often attributed to its origin from the arachnoid cells, which produce a characteristic whorled pattern under microscopic examination. In contrast to gliomas, meningiomas have a distinct histological appearance, with a higher density of fibrous or psammomatous components.

**Why Each Wrong Option is Incorrect**
**Option A:** Diffuse astrocytoma is a high-grade glioma with a more aggressive clinical course, characterized by rapid growth and infiltration into surrounding brain tissue. It is not typically classified as low-grade.
**Option B:** Anaplastic astrocytoma is another high-grade glioma, distinguished by its rapid growth and high mitotic activity, making it a more malignant option than meningioma.
**Option C:** Glioblastoma multiforme is the most aggressive type of glioma, with a poor prognosis and rapid progression. It is characterized by its high cellularity, mitotic activity, and necrosis, making it a high-grade tumor.
**Option D:** This option is actually correct, so we'll skip it.

**Clinical Pearl / High-Yield Fact**
Meningiomas are often associated with a characteristic "dural tail" sign on imaging studies, which represents the tumor's attachment to the dura mater. This radiologic feature can aid in the diagnosis of meningioma and distinguish it from other types of brain tumors.

✓ Correct Answer: D. Meningioma