❓ 質問 According to the passage, which of the following best describes the role of the starfish Pisaster ochraceus in Paine's experiments?
- A. A. It was a keystone species because its removal caused a decline in mussel populations.
- B. B. It acted as an ecosystem engineer by creating physical structures for other species.
- C. C. It was a predator whose presence maintained high species diversity in the intertidal zone.
- D. D. It was a competitive dominant that monopolized the rocky substrate when present.