## **Core Concept**
The question tests understanding of molecular biology, specifically the genetic code and **stop codons** (also known as termination codons). These codons signal the termination of protein synthesis in a cell.

## **Why the Correct Answer is Right**
The correct answer, , codes for the amino acid **tryptophan** and is a **start codon** as well as a codon for an amino acid. The other options, , , and , are recognized as **stop codons** or termination codons in the genetic code, signaling the end of the protein synthesis process.

## **Why Each Wrong Option is Incorrect**
- **Option A:** is one of the three stop codons.
- **Option B:** is another stop codon.
- **Option D:** is also a stop codon.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that there are three stop codons: , , and . The codon is unique because it not only codes for **tryptophan** but also serves as the **start codon** for protein synthesis, directing the ribosome to begin translation.

## **Correct Answer:** .