**Core Concept**
The development of the eye involves a complex interplay of multiple genes and signaling pathways, but a key regulator is the gene responsible for the formation of the optic vesicle and subsequent eye development.

**Why the Correct Answer is Right**
The correct answer is **PAX6**, a paired-box transcription factor that plays a crucial role in the development of the eye, brain, and pancreas. PAX6 is highly expressed in the optic vesicle and regulates the expression of other genes involved in eye development, including those involved in lens formation and retinal differentiation. Mutations in PAX6 can lead to eye abnormalities, such as aniridia and coloboma.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not specified, so we will move on to the next one.

**Option B:** This option is not specified, so we will move on to the next one.

**Option C:** This option is not specified, so we will move on to the next one.

**Clinical Pearl / High-Yield Fact**
PAX6 is a key regulator of eye development, and mutations in this gene can lead to a range of eye abnormalities. It is also involved in the development of other organs, including the brain and pancreas.

**Correct Answer:** D. PAX6