**Core Concept**
Retinoblastoma is a rare form of cancer that affects the retina of the eye and is the most common intraocular malignancy in children. It is characterized by the uncontrolled growth of immature cells in the retina.

**Why the Correct Answer is Right**
Retinoblastoma is a hereditary tumor that arises due to mutations in the RB1 gene, which is a tumor suppressor gene. This gene plays a crucial role in regulating the cell cycle, preventing cell division, and promoting apoptosis. Mutations in the RB1 gene can lead to the development of retinoblastoma, often at a young age. In fact, children with bilateral retinoblastoma have a high likelihood of carrying a germline mutation in the RB1 gene.

**Why Each Wrong Option is Incorrect**
**Option A:** Leukemia is a type of cancer that affects the blood and bone marrow, but it is not the most common inherited childhood tumor. While leukemia can be inherited, it is more commonly associated with acquired genetic mutations.
**Option B:** Neuroblastoma is a type of cancer that arises from immature nerve cells and is the most common extracranial solid tumor in children. However, it is not typically inherited and is more often associated with somatic mutations.
**Option D:** Wilms tumor is a type of kidney cancer that affects children, but it is not the most common inherited childhood tumor. While some cases of Wilms tumor may be associated with genetic syndromes, it is not as strongly linked to inherited mutations as retinoblastoma.

**Clinical Pearl / High-Yield Fact**
Retinoblastoma often presents with leukocoria (white pupillary reflex), strabismus, or vision loss in one eye. Early detection and treatment are critical to prevent tumor spread and improve outcomes.

**✓ Correct Answer: C. Retinoblastoma**