Which of the following is nutritionally essential amino acid for humans

Options

A. Arginine
B. Aspartic acid
C. Glycine
D. Phenylalanine

Answer

To determine which of the following is a nutritionally essential amino acid for humans, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Amino Acids**: Amino acids are the building blocks of proteins. They are categorized into two groups: essential and non-essential amino acids.

2. **Define Essential Amino Acids**: Essential amino acids cannot be synthesized by the human body and must be obtained through diet.

3. **List Essential Amino Acids**: There are nine essential amino acids for humans:
- Leucine
- Isoleucine
- Valine
- Histidine
- Lysine
- Methionine
- Tryptophan
- Phenylalanine
- Threonine

4. **Analyze the Options**: The options given are:
- Arginine
- Aspartic acid
- Glycine
- Phenylalanine

5. **Identify Essential Amino Acids in Options**: Among the options, we need to check which one is listed as an essential amino acid.
- Arginine is considered a semi-essential amino acid (conditionally essential).
- Aspartic acid and glycine are non-essential amino acids.
- Phenylalanine is one of the nine essential amino acids.

6. **Conclusion**: The only essential amino acid from the provided options is **Phenylalanine**.

### Final Answer:
**Phenylalanine is the nutritionally essential amino acid for humans.**

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