Taxonomical aid key used for identification of plants and animals is.

Options

A. Based on the similarities and dissimilarities
B. Based on the contrasting characters generally in a pairs called couplet
C. Generally analytical in nature
D. All of the above

Answer

To answer the question regarding the taxonomical aid key used for the identification of plants and animals, we can break down the solution into the following steps:

### Step-by-Step Solution:

1. **Understanding Taxonomical Aids**: Taxonomical aids are tools that help in the identification and classification of organisms. They provide a systematic approach to categorize living beings based on their characteristics.

2. **Identifying the Key Features**: The taxonomical aid key, often referred to as a dichotomous key, is specifically designed to identify organisms based on their similarities and differences. It typically presents a series of choices that lead the user to the correct identification.

3. **Couplets in Taxonomical Keys**: The key is structured using 'couplets', which are pairs of contrasting statements or characteristics. Each couplet guides the user to the next step in the identification process, based on the presence or absence of specific traits.

4. **Analytical Nature of the Key**: The taxonomical aid key is analytical in nature, meaning it breaks down the identification process into logical steps. This analytical approach allows for systematic comparisons between different organisms.

5. **Conclusion**: Given the features of the taxonomical aid key, we can conclude that it is used for identifying plants and animals based on similarities and dissimilarities, employs contrasting characters in couplets, and is analytical in nature. Therefore, the correct answer to the question is "all of the above".

### Final Answer:
The taxonomical aid key used for identification of plants and animals is: **All of the above**.

---