ICBN is

Options

A. International Code of Biological Naming
B. International Code for Botanical Nomenclature
C. International Class of Biological Nomenclature
D. International Classification of Biological Nomenclature.

Answer

### Step-by-Step Solution:

1. **Understanding the Acronym ICBN**:
- The question asks for the full form of the acronym ICBN.
- We need to identify what each letter stands for.

2. **Breaking Down the Options**:
- The options provided are:
1. International code of biological naming
2. International code for botanical nomenclature
3. International class of biological nomenclature
4. International classification of biological nomenclature

3. **Identifying the Correct Option**:
- The correct expansion of ICBN is "International Code for Botanical Nomenclature".
- This is because ICBN specifically deals with the naming conventions of plants, algae, and fungi.

4. **Understanding the Context**:
- ICBN is a set of rules and recommendations dealing with the naming of plants and other organisms in the botanical field.
- It is important to note that ICBN is related to taxonomy, which involves identification, classification, and nomenclature.

5. **Conclusion**:
- The correct answer to the question "ICBN is" is option 2: International code for botanical nomenclature.