**Core Concept**
The question is testing the knowledge of congenital conjunctival tumors. Conjunctival tumors can be benign or malignant, and some are more common in children than others.

**Why the Correct Answer is Right**
The correct answer is **C. Congenital Epibulbar Dermoids**. Congenital epibulbar dermoids are the most common type of congenital conjunctival tumors. They are benign growths that arise from the conjunctiva and are usually present at birth. They are thought to occur due to the abnormal migration of surface ectoderm cells during embryonic development.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because **Congenital Cysts** are not the most common type of congenital conjunctival tumors. While they can occur, they are less common than congenital epibulbar dermoids.

**Option B:** This option is incorrect because **Chalazion** is a type of conjunctival tumor, but it is not congenital. It is a benign growth that occurs due to the blockage of a Meibomian gland.

**Option D:** This option is incorrect because **Pterygium** is a type of conjunctival tumor, but it is not congenital. It is a benign growth that occurs due to chronic exposure to UV radiation.

**Clinical Pearl / High-Yield Fact**
It's worth noting that congenital epibulbar dermoids are usually located on the temporal side of the eye and can be associated with other congenital anomalies. They are often diagnosed at birth or in early childhood.

**Correct Answer: C. Congenital Epibulbar Dermoids**