The World Wildlife Fund has declared that global warming, a phenomenon most scientists agree to be caused by human beings in burning fossil fuels, will create havoc among migratory birds by altering the environment in ways harmful to their habitats.



  1. a phenomenon most scientists agree to be caused by human beings in burning fossil fuels,

Human beings are not IN Burning fossil fuel. This would make the sentence illogical. Eliminate


(B) a phenomenon most scientists agree that is caused by fossil fuels burned by human beings,

What is global warming caused by?

It is caused by- fossil fuels. Eliminate


(C) a phenomenon that most scientists agree is caused by human beings' burning of fossil fuels,

a phenomenon that most scientists agree is …. modifies Global warming. 

What is global warming caused by?


It is caused by-  human beings' burning of fossil fuels


(D) which most scientists agree on as a phenomenon caused by human beings who burn fossil fuels,

What is global warming caused by?

It is caused by- Human beings who.. ( more information about human beings) Eliminate


(E) which most scientists agree to be a phenomenon caused by fossil fuels burned by human beings,


 What is global warming caused by?

It is caused by- fossil fuels. Eliminate


C is the best choice.