Sulphur containing amino acid is
**Core Concept**
The question tests knowledge of amino acid structure, specifically focusing on those containing **sulphur**. Amino acids are the building blocks of proteins, and their unique side chains contribute to the overall function and structure of proteins.
**Why the Correct Answer is Right**
The correct answer contains **methionine** and **cysteine**, which are indeed the sulphur-containing amino acids. **Methionine** is an essential amino acid, meaning it cannot be synthesized by the body and must be obtained through the diet. **Cysteine**, on the other hand, is considered semi-essential because it can be synthesized from **methionine**.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not contain any sulphur-containing amino acids.
**Option B:** Incorrect as it doesn't specify the correct sulphur-containing amino acids.
**Option D:** This option is also incorrect as it doesn't list the sulphur-containing amino acids.
**Clinical Pearl / High-Yield Fact**
Remembering that **methionine** and **cysteine** are the sulphur-containing amino acids is crucial, especially in the context of **homocysteine** metabolism, where **methionine** plays a key role.
**Correct Answer:** C. Methionine and Cysteine