Which of the following statement (s) about taxonomic aids is/are true
I. Keys are used to identify plants and animals based on similarities and disimilarities.
II. Flora contains the account of habitat and distribution of plants in a given area.
III. Flora provides an index to the plant species found in a particular area.
IV. Monographs provide information for identification of species found in an area

Options

A. I and II only
B. I, II and III only
C. I and IV only
D. I only

Answer

To determine which statements about taxonomic aids are true, let's analyze each statement one by one:

1. **Statement I**: "Keys are used to identify plants and animals based on similarities and dissimilarities."
- **Analysis**: This statement is true. Taxonomic keys, also known as dichotomous keys, are tools that help in the identification of organisms by presenting a series of choices that lead the user to the correct name of a given item. These keys rely on the similarities and differences among the organisms.

2. **Statement II**: "Flora contains the account of habitat and distribution of plants in a given area."
- **Analysis**: This statement is also true. Flora refers to the plant life occurring in a particular region or time, generally the naturally occurring or indigenous plant life. It provides information about the habitat and distribution of various plant species in that area.

3. **Statement III**: "Flora provides an index to the plant species found in a particular area."
- **Analysis**: This statement is true as well. Flora often includes an index or a list of the plant species found in a specific area, which helps researchers and botanists identify and study the plant life of that region.

4. **Statement IV**: "Monographs provide information for identification of species found in an area."
- **Analysis**: This statement is incorrect. Monographs are comprehensive studies that focus on a single taxon (such as a family or genus) and provide detailed information about that group, including taxonomy, morphology, and ecology. They do not specifically focus on identifying species found in a particular area.

**Conclusion**: The true statements are I, II, and III. Therefore, the correct answer is that statements I, II, and III are true.

### Final Answer:
The true statements about taxonomic aids are:
- I, II, and III only.