Guanosine is a

Options

A. Nucleoside
B. Nilrogen base
C. Nuclootide
D. Pyrimidine

Answer

### Step-by-Step Solution:

1. **Understanding Guanosine**:
- Guanosine is a chemical compound that falls under the category of nucleosides.

2. **Defining Nucleosides**:
- A nucleoside consists of a nitrogenous base attached to a sugar molecule. In the case of guanosine, the nitrogenous base is guanine, and the sugar is ribose.

3. **Identifying Components**:
- Guanosine is made up of:
- **Nitrogen Base**: Guanine
- **Sugar**: Ribose

4. **Evaluating the Options**:
- **Option 1: Nucleoside** - This is correct because guanosine fits the definition of a nucleoside.
- **Option 2: Nitrogen Base** - This is incorrect because guanosine is not just a nitrogen base; it is a nucleoside that contains a nitrogen base.
- **Option 3: Nucleotide** - This is incorrect because nucleotides also contain a phosphate group, which guanosine does not have.
- **Option 4: Pyrimidine** - This is incorrect because guanine is a purine, not a pyrimidine.

5. **Conclusion**:
- Based on the definitions and evaluations, the correct answer is that guanosine is a **nucleoside**.

### Final Answer:
Guanosine is a **nucleoside**.

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