**Core Concept**
Medulloblastoma is a type of **primitive neuroectodermal tumor (PNET)** that originates in the **cerebellum**, which is part of the **central nervous system (CNS)**. It is the most common **malignant brain tumor** in children.

**Why the Correct Answer is Right**
Medulloblastoma is indeed **radiosensitive**, meaning it responds well to **radiation therapy**, which is a common treatment modality for this tumor. It also has a tendency to **spread through the cerebrospinal fluid (CSF)**, making **CSF dissemination** a concern.

**Why Each Wrong Option is Incorrect**
**Option C:** Surgical treatment is indeed done for medulloblastoma, as **gross total resection** is often the initial step in management.
**Option D:** While it's true that medulloblastoma occurs in a **young age group**, this option is not the most specific or accurate statement about the tumor.
**Option E:** Medulloblastoma typically occurs in the **infratentorial region**, not supratentorially.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that medulloblastoma has a high propensity for **CSF spread**, which necessitates **craniospinal irradiation** as part of its treatment.

**Correct Answer:** A. Radiosensitive tumor