❓ 質問 According to the passage, which of the following best describes the role of a keystone species?
- A. A species that is the most abundant in an ecosystem and therefore has the largest biomass.
- B. A species that has an effect on its ecosystem that is much greater than its abundance would suggest.
- C. A species that only includes top predators like starfish, not species that provide resources.
- D. A species that is always identified easily and consistently across different ecosystems.