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❓ 题目 What is the main purpose of the passage?

A. A. To argue that the keystone species concept is outdated and should be discarded
B. B. To describe the history and ongoing relevance of the keystone species concept in ecology
C. C. To explain Paine's experiment and its immediate results in detail
D. D. To compare keystone species with functional redundancy in ecosystems

B. To describe the history and ongoing relevance of the keystone species concept in ecology