Define biodiversity.

Biodiversity refers to the variety of living organisms within a specific ecosystem or across the planet as a whole. This includes not only the diversity of species present but also the genetic diversity within those species and the variety of ecosystems themselves. A rich biodiversity is crucial as it enables ecosystems to function effectively, provides resilience against environmental changes, and contributes to the overall health of the planet.

The emphasis on the variety of living organisms highlights the importance of maintaining different species, as each plays a unique role in the ecosystem, contributing to functions such as pollination, nutrient cycling, and food webs. Biodiversity is vital for ecological stability and contributes to the services ecosystems provide to humans, such as clean air, water, and resources.

The other options do not fully capture what biodiversity encompasses. Simply counting the number of habitats inaccurately reflects the complex relational dynamics within ecosystems. The total mass of organisms does not provide insight into the various species or their interactions. While interactions between different species can influence biodiversity, that aspect alone does not define the term. Therefore, understanding biodiversity as the variety of living organisms provides a clearer and more comprehensive definition.