**Core Concept**
The development of ocular structures is a complex process involving the interaction of multiple embryonic layers. Surface ectoderm gives rise to the cornea, lens, and conjunctiva, while other structures have different embryonic origins.

**Why the Correct Answer is Right**
The correct answer is derived from a different embryonic layer. The retina is a neural structure derived from the optic cup, which forms from the invagination of the neural ectoderm. This process involves the differentiation of neuroblasts into various retinal cell types, including photoreceptors and bipolar cells.

**Why Each Wrong Option is Incorrect**
**Option A:** The cornea is indeed derived from surface ectoderm, which covers the anterior portion of the eye and gives rise to the epithelial layer of the cornea.
**Option B:** The lens is also derived from surface ectoderm, which invaginates to form the lens pit and eventually differentiates into lens fibers.
**Option C:** The conjunctiva is a membrane covering the anterior portion of the eye and is derived from surface ectoderm.

**Clinical Pearl / High-Yield Fact**
The retina is a highly specialized neural tissue that requires precise development and differentiation to function properly. Abnormalities in retinal development can lead to various ocular disorders, including retinitis pigmentosa and macular degeneration.

**Correct Answer: D**