The basis of modern taxonomic studies are :-
(a) External and internal structure
(b) Structure of cell
(c) Development process
(d) Ecological informations

Options

A. a and b
B. a, b and c
C. a, c and d
D. All a, b, c and d

Answer

To solve the question regarding the basis of modern taxonomic studies, we need to analyze each option provided:

1. **Understanding Taxonomy**: Taxonomy is the science of classification of organisms. It involves categorizing organisms based on various criteria.

2. **Option (a) External and internal structure**: This refers to the morphological characteristics of organisms. The external structure includes features like shape, size, and color, while the internal structure involves anatomy and organ systems. Both are crucial for identifying and classifying organisms.

3. **Option (b) Structure of cell**: The cellular structure is fundamental in taxonomy as it provides insights into the classification at the microscopic level. Different organisms have distinct cellular structures, which can indicate their evolutionary relationships.

4. **Option (c) Development process**: The developmental processes of organisms, such as embryonic development, can reveal evolutionary relationships and help classify organisms based on their life cycles.

5. **Option (d) Ecological information**: Understanding the ecological roles and interactions of organisms within their environments is also important in taxonomy. It helps in understanding the relationships between different organisms and their habitats.

6. **Conclusion**: All the options (a, b, c, and d) contribute to modern taxonomic studies. Therefore, the correct answer is that the basis of modern taxonomic studies includes all of the above aspects.

**Final Answer**: All of the above (a, b, c, and d).

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