**Core Concept**
Retinoblastoma is a malignant intraocular tumor predominantly affecting children, arising from the retina. It is a neuroectodermal tumor that exhibits a high degree of cellular differentiation.

**Why the Correct Answer is Right**
Retinoblastoma is the most common intraocular tumor in children, accounting for approximately 3% of all pediatric cancers. It typically presents with leukocoria (white pupillary reflex) or strabismus. The tumor arises from the primitive neuroectodermal cells of the retina, and its progression is influenced by the loss of function of the RB1 tumor suppressor gene. The RB1 gene mutations can be inherited in an autosomal dominant pattern, or they can occur spontaneously.

**Why Each Wrong Option is Incorrect**
**Option A:** Melanoma is a more common intraocular tumor in adults, particularly those with a history of uveal melanoma in the family. It arises from the uveal tract, which includes the iris, ciliary body, and choroid.
**Option B:** Medulloepithelioma is a rare, malignant intraocular tumor that typically affects children, but it is much less common than retinoblastoma. It arises from the embryonic medullary epithelium of the ciliary body.
**Option C:** Hemangioma is a benign vascular tumor that can occur in the orbit or eyelid, but it is not an intraocular tumor. It typically presents as a congenital or infantile lesion.

**Clinical Pearl / High-Yield Fact**
Retinoblastoma is a highly malignant tumor that requires prompt diagnosis and treatment to prevent metastasis and improve survival rates. The presence of leukocoria or strabismus in a child should raise suspicion for retinoblastoma.

**Correct Answer:** C.