Lysine and tryptophan are

Options

A. proteins
B. non-essential amino acids
C. essential amino acids
D. aromatic amino acids

Answer

### Step-by-Step Solution:

1. **Identify the Question**: The question asks about lysine and tryptophan.

2. **Define Amino Acids**: Understand that lysine and tryptophan are both amino acids. Amino acids are the building blocks of proteins.

3. **List the Types of Amino Acids**: There are 20 standard amino acids, which can be categorized into essential and non-essential amino acids. Essential amino acids are those that cannot be synthesized by the body and must be obtained from the diet.

4. **Identify Lysine and Tryptophan**: Both lysine and tryptophan are classified as essential amino acids. This means that the body cannot produce them, and they must be ingested through food.

5. **Explain Their Role**: Lysine and tryptophan play crucial roles in protein synthesis and are vital for various bodily functions, including hormone production and neurotransmitter synthesis.

6. **Conclude the Answer**: Therefore, the correct answer to the question is that lysine and tryptophan are essential amino acids.

### Final Answer:
Lysine and tryptophan are essential amino acids.

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