**Core Concept**
The question is testing the student's knowledge of the most common type of eye tumor, which is a type of neoplasm affecting the eye.

**Why the Correct Answer is Right**
The correct answer is a benign tumor of the uveal tract, specifically the choroid, and is the most common primary intraocular malignancy in adults. It is thought to arise from the melanocytes of the choroid. The tumor is typically unilateral, and the most common presentation is a change in vision in one eye. The pathogenesis is related to mutations in the BAP1 gene, which is a tumor suppressor gene.

**Why Each Wrong Option is Incorrect**
**Option A:** Melanoma is incorrect because while it is a type of eye tumor, it is not the most common type.
**Option B:** Squamous cell carcinoma is incorrect because it is a type of skin cancer and is not typically associated with the eye.
**Option C:** Retinoblastoma is incorrect because it is a type of eye tumor, but it is primarily a pediatric disease and not the most common type in adults.

**Clinical Pearl / High-Yield Fact**
The term "uveitis" refers to inflammation of the uveal tract, which includes the iris, ciliary body, and choroid. Uveitis can be a presenting feature of various systemic diseases, including sarcoidosis, tuberculosis, and multiple sclerosis.

**Correct Answer:** C. Melanoma of the choroid.