TOEFL読解

❓ 質問 According to the passage, which of the following best describes the main idea regarding keystone species?

A. A. Keystone species are always top predators whose removal causes a decrease in biodiversity.
B. B. Keystone species have a disproportionately large ecological impact relative to their abundance, and their loss can trigger cascading effects.
C. C. The keystone species concept is universally accepted and has no limitations in its application.
D. D. Keystone species are defined solely by their abundance and size in a given ecosystem.

B. Keystone species have a disproportionately large ecological impact relative to their abundance, and their loss can trigger cascading effects.