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❓ 题目 According to the passage, what is the primary distinction between a keystone species and a dominant species?

A. Keystone species are always predators, whereas dominant species are usually herbivores.
B. Keystone species have a large effect relative to their abundance, while dominant species exert influence through biomass.
C. Keystone species are rare, whereas dominant species are always abundant in numbers.
D. Keystone species only exist in marine environments, while dominant species are found in terrestrial ecosystems.

Keystone species have a large effect relative to their abundance, while dominant species exert influence through biomass.