Which one of the following is alcoholic amino acid pair ?
(a) Tyrosine and serine
(b) Theronine and serine
(c) Phenylalanine and tyrosine
(d) Tryptophan and phenylalanine

Options

A. tyrosine and serine
B. Theronine and serine
C. phenylalanine and tyrosine
D. Tryptophan and phenylalanine

Answer

To solve the question of which one of the following pairs is an alcoholic amino acid pair, we need to identify the amino acids that contain hydroxyl (–OH) groups.

### Step-by-Step Solution:

1. **Understanding Alcoholic Amino Acids**:
- Alcoholic amino acids are those that contain hydroxyl groups (–OH) in their side chains. The two main alcoholic amino acids are serine and threonine.

2. **Analyzing the Options**:
- **Option (a)**: Tyrosine and serine
- Tyrosine contains a phenolic –OH group, but it is not classified as an alcoholic amino acid in the same sense as serine and threonine.
- **Option (b)**: Threonine and serine
- Both threonine and serine contain hydroxyl groups in their side chains. Therefore, this option is a pair of alcoholic amino acids.
- **Option (c)**: Phenylalanine and tyrosine
- Phenylalanine does not have a hydroxyl group, and while tyrosine does, this pair does not qualify as an alcoholic amino acid pair.
- **Option (d)**: Tryptophan and phenylalanine
- Neither of these amino acids contains a hydroxyl group, so this option is also incorrect.

3. **Conclusion**:
- The correct answer is **(b) Threonine and serine**, as both are alcoholic amino acids.

### Final Answer:
(b) Threonine and serine