❓ 题目 According to the passage, what is a key limitation of the keystone species concept as noted by modern ecologists?
- A. A) It overemphasizes the role of predators while ignoring ecosystem engineers.
- B. B) The effect of a keystone species can vary depending on environmental context.
- C. C) It is difficult to identify keystone species in marine environments.
- D. D) The concept was based solely on experiments with starfish and lacks generality.