❓ 質問 According to the passage, what is a major criticism of the keystone species concept?
- A. A. Keystone species are always predators, which is too narrow a definition.
- B. B. The term is overused, and many species may have redundant ecological roles.
- C. C. It is impossible to identify keystone species in real ecosystems.
- D. D. The concept only applies to terrestrial environments, not marine ones.