**Core Concept**
The question tests knowledge of an inborn error of metabolism affecting the choroid, a layer of blood vessels and connective tissue between the sclera and retina. Essential atrophy of the choroid, also known as gyrate atrophy, is a rare inherited condition.

**Why the Correct Answer is Right**
Gyrate atrophy is caused by a deficiency of the enzyme ornithine aminotransferase (OAT), which is responsible for converting ornithine to glutamate. This enzymatic defect leads to an accumulation of ornithine in the blood and tissues, including the choroid. Over time, the choroid degenerates, resulting in progressive vision loss. Lysine metabolism is also affected in this condition, as it competes with ornithine for the OAT enzyme. Elevated lysine levels can further contribute to the disease's pathogenesis.

**Why Each Wrong Option is Incorrect**
* **Option A:** Cystine is an amino acid involved in cystinosis, a different inborn error of metabolism characterized by lysosomal storage of cystine. It is not related to gyrate atrophy or essential atrophy of the choroid.
* **Option B:** Cysteine is an amino acid that can be involved in various metabolic disorders, but it is not directly related to gyrate atrophy.
* **Option C:** Arginine is an amino acid that plays a role in various physiological processes, but it is not involved in the pathogenesis of gyrate atrophy.

**Clinical Pearl / High-Yield Fact**
Gyrate atrophy is an autosomal recessive disorder, meaning that affected individuals inherit two defective copies of the OAT gene, one from each parent. Early diagnosis and management are crucial to slow the progression of vision loss and prevent further complications.

**✓ Correct Answer: D. Ornithine E Lysine**