请教张慧雯老师，本题我的定位点和思路， Moreover, whereas P. ochraceus occupies an unambiguous keystone role on wave-exposed rocky headlands,in more wave-sheltered habitats the impact of P. ochraceus predation is weak or nonexistent, and at certain sites sand burial is responsible for eliminating mussels.同时把重点放在了这句话： Keystone status appears to depend on context, whether of particular geography or of such factors as community diversity (for example, a reduction in species diversity may thrust more of the remaining species into keystone roles) and length of species interaction (since newly arrived species in particular may dramatically affect ecosystems).大概的理解就是k的地位和地理要素比如diversity和 length of species interaction 挂钩，然后我就选了e，事后觉得这个选项within some habitats occupied by P. ochraceus可能有点问题，但是当时根据我重点关注的这句话我也觉得a和原文没关系（虽然上句话有提到），请老师指出我的问题。

请教张慧雯老师，本题我的定位点和思路， Moreover, whereas P. ochraceus occupies an unambiguous keystone role on wave-exposed rocky headlands,in more wave-sheltered habitats the impact of P. ochraceus predation is weak or nonexistent, and at certain sites sand burial is responsible for eliminating mussels.同时把重点放在了这句话： Keystone status appears to depend on context, whether of particular geography or of such factors as community diversity (for example, a reduction in species diversity may thrust more of the remaining species into keystone roles) and length of species interaction (since newly arrived species in particular may dramatically affect ecosystems).大概的理解就是k的地位和地理要素比如diversity和 length of species interaction 挂钩，然后我就选了e，事后觉得这个选项within some habitats occupied by P. ochraceus可能有点问题，但是当时根据我重点关注的这句话我也觉得a和原文没关系（虽然上句话有提到），请老师指出我的问题。