a) Humans depend upon other organisms for food and oxygen
Explanation:
Biodiversity refers to the richness in the species of organisms on Earth i.e the variety of biological organisms on the Earth. The importance of biodiversity cannot be overemphasized because of our dependence on the sustainability of biodiversity in our ecosystems.
The loss of biodiversity, which is becoming rampant by the day, is a major concern to us because we humans depend upon other organisms for food and oxygen. Humans are strictly heterotrophic and hence are reliant on variety of organisms for food. Plants also release oxygen gas via their photosynthetic process, which is key to our survival as a population.