Which of the following best defines biodiversity?

Biodiversity is best defined as the full range of life forms on Earth. This concept encompasses the variety of species, genetic diversity within species, and the variety of ecosystems present in a region or throughout the planet. Biodiversity is crucial for maintaining ecosystem functions and resilience, contributing to ecological balance, and providing resources such as food, medicine, and clean air and water.

The other options misrepresent the concept of biodiversity. For example, focusing solely on nature-based tourism options limits the understanding of biodiversity to a commercial aspect and overlooks the broader biological and ecological significance. The option about the number of organizations promoting wildlife is similarly narrow, as it does not encompass the actual variety of life forms themselves but rather the social and organizational efforts around wildlife conservation. Lastly, considering the ecological footprint of human activities relates more to sustainability and environmental impact rather than directly defining biodiversity, which is centered on the diversity of life itself.