**Core Concept**
Cystinuria is a genetic disorder characterized by the excessive excretion of cystine and other dibasic amino acids in the urine due to impaired transport in the kidneys. This condition is caused by mutations in the SLC3A1 or SLC7A9 genes, leading to a defect in the cystine transporter in the proximal tubules.

**Why the Correct Answer is Right**
Cystinuria involves the abnormal excretion of cystine, lysine, arginine, and ornithine due to their impaired reabsorption in the kidneys. These amino acids are transported by the rBAT/b0,+AT (SLC3A1/SLC7A9) transporter in the proximal tubules. The defect in this transporter leads to the accumulation of these amino acids in the urine, resulting in cystine stones and other complications.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided, so we'll proceed with the other options.
**Option B:** Incorrect - Arginine is indeed one of the amino acids secreted in cystinuria.
**Option C:** Incorrect - Ornithine is another dibasic amino acid that is excessively excreted in cystinuria.
**Option D:** Incorrect - Lysine is the fourth dibasic amino acid involved in cystinuria, similar to arginine and ornithine.

**Clinical Pearl / High-Yield Fact**
Cystinuria is an autosomal recessive disorder, and genetic testing can help confirm the diagnosis. Treatment involves increasing urine pH, reducing cystine solubility, and preventing the formation of cystine stones.

**Correct Answer: D. Lysine is not one of the primary amino acids involved in cystinuria (cystine, lysine, arginine, and ornithine are the four).