Explanation:

The correct answer is option 'D', which states that the wide range of different animal species, plants, grass, and birds in an area constitute both biodiversity and flora and fauna of that area. Let's understand this in detail:

Biodiversity:
Biodiversity refers to the variety of life forms present in a particular habitat or ecosystem. It includes all living organisms, including plants, animals, microorganisms, and their interactions with each other and their environment.

Flora and Fauna:
Flora refers to the plant species present in a particular area, while fauna refers to the animal species. Flora and fauna together encompass all the plant and animal life found in an ecosystem.

Significance of Biodiversity:
Biodiversity is crucial for maintaining the balance and stability of ecosystems. It provides various ecosystem services such as food, medicine, clean air and water, pollination, nutrient cycling, and climate regulation. Biodiversity also plays a vital role in maintaining the overall health and resilience of the planet.

Examples of Biodiversity:
1. Animal Species: The presence of different animal species like mammals, birds, reptiles, amphibians, and insects in an area contributes to its biodiversity. Each species has unique characteristics, behaviors, and roles within the ecosystem.
2. Plant Species: The variety of plant species, including trees, shrubs, herbs, and grasses, adds to the biodiversity of an area. Different plants provide habitat, food, and shelter for various animal species.
3. Grass: Grasses form an essential part of many ecosystems. They provide food for herbivores, prevent soil erosion, and contribute to the overall productivity of the ecosystem.
4. Birds: The presence of various bird species in an area indicates a diverse and healthy ecosystem. Birds play crucial roles such as pollination, seed dispersal, and insect control.

Conclusion:
In conclusion, the wide range of different animal species, plants, grass, and birds in an area constitute both biodiversity and flora and fauna of that area. Biodiversity and the presence of diverse flora and fauna are essential for the functioning and sustainability of ecosystems.