Which of the following is a nucleoside

Options

A. Adenylic acid
B. Cytosine
C. Uridine
D. Thiamine

Answer

To determine which of the given options is a nucleoside, we need to understand the definition of a nucleoside and analyze each option accordingly.

### Step-by-Step Solution:

1. **Understand the Definition of a Nucleoside**:
- A nucleoside is a compound that consists of a nitrogenous base (nucleobase) attached to a five-carbon sugar (ribose or deoxyribose). It does not include any phosphate groups.

2. **Analyze Each Option**:
- **Option A: Adenylic acid**:
- Adenylic acid is a nucleotide, which consists of a nucleoside (adenosine) plus one or more phosphate groups. Therefore, it is not a nucleoside.

- **Option B: Cytosine**:
- Cytosine is a nitrogenous base, but it does not have a sugar component attached to it. Hence, it is not a nucleoside.

- **Option C: Uridine**:
- Uridine is a nucleoside that consists of the nitrogenous base uracil attached to a ribose sugar. Therefore, this is a valid nucleoside.

- **Option D: Thymine**:
- Thymine is also a nitrogenous base and does not have a sugar component attached. Thus, it is not a nucleoside.

3. **Conclusion**:
- Based on the analysis, the only option that qualifies as a nucleoside is **Option C: Uridine**.

### Final Answer:
The correct answer is **C. Uridine**.

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