请问哪个选项可以更好地把句子补充完整?The World Wildlife Fund has declared that global warming, _____________________________, will create havoc among migratory birds by altering the environment in ways harmful to their habitats.
A.
a phenomenon that most scientists agree is caused by human beings in buring fossil fuels
B.
a phenomenon that most scientists agree is caused by fossil fuels burned by human beings
C.
a phenomenon that most scientists agree is caused by human beings' buring of fossil fuels
D.
a phenomenon that is caused by fossil fuels burned by human beings