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

A. A. Keystone species are always predators, while dominant species are not.
B. B. Keystone species have effects that cannot be replaced by other species, while dominant species are functionally redundant.
C. C. Dominant species are more abundant than keystone species, but both have similar ecological impacts.
D. D. Keystone species are found only in marine ecosystems, while dominant species are terrestrial.

B. Keystone species have effects that cannot be replaced by other species, while dominant species are functionally redundant.