**Core Concept**
Retinoblastoma is a malignant tumor of the retina that primarily affects children. It is characterized by the uncontrolled growth of immature retinal cells, leading to the formation of a solid tumor within the eye.

**Why the Correct Answer is Right**
Retinoblastoma is the most common primary intraocular neoplasm in children, accounting for approximately 3-4% of all childhood cancers. The tumor arises from the primitive neuroectodermal cells of the retina, which are responsible for the formation of the visual pathway. The genetic basis of retinoblastoma involves mutations in the RB1 gene, a tumor suppressor gene that regulates cell cycle progression. These mutations can occur spontaneously or be inherited in an autosomal dominant pattern. The clinical presentation of retinoblastoma includes leukocoria (white pupillary reflex), strabismus, and vision loss.

**Why Each Wrong Option is Incorrect**
**Option A:** Metastasis refers to the spread of cancer cells from a primary tumor to other parts of the body. While metastatic tumors can involve the eye, they are not primary intraocular neoplasms.

**Option C:** Basal cell carcinoma is a type of skin cancer that rarely affects the eye. It is not a common primary intraocular neoplasm in children.

**Option D:** Squamous cell carcinoma is another type of skin cancer that can involve the eye, but it is not a primary intraocular neoplasm in children.

**Clinical Pearl / High-Yield Fact**
Retinoblastoma can be diagnosed prenatally or at birth, and early detection is critical for treatment and survival. The International Classification of Retinoblastoma (ICRB) categorizes the disease into four stages, with stage I being the least advanced and stage IV being the most advanced.

**✓ Correct Answer: B. Retinoblastoma**