OG SC01987 有没有大佬能帮我分析一下这个句子结构呜呜呜呜

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                                                                                                                                                [size=11.000000pt]The World Wildlife Fund has declared that global warming, a phenomenon most scientistsagree to be caused by human beings in burning fossil fuels, will create havoc amongmigratory birds by altering the environment in ways harmful to their habitats.
A. a phenomenon most scientists agree to be caused by human beings in burning fossilfuels,
B. a phenomenon most scientists agree that is caused by fossil fuels burned by humanbeings,
C. a phenomenon that most scientists agree is caused by human beings’ burning of fossilfuels,
D. which most scientists agree on as a phenomenon caused by human beings who burnfossil fuels,
E. which most scientists agree to be a phenomenon caused by fossil fuels burned byhuman beings,
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[size=14.6667px]这个题正确选项C中，that引导的定语从句里most scientist agree是什么成分，我认为that是定语从句的主语，is caused是谓语，但这样分析[size=14.6667px]most scientist agree就不知道是做什么成分了
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