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.

• Aa phenomenon most scientists agree to be caused by human beings in burning fossil fuels,  
• Ba phenomenon most scientists agree that is caused by fossil fuels burned by human beings,  
• Ca phenomenon that most scientists agree is caused by human beings' burning of fossil fuels,  
• Dwhich most scientists agree on as a phenomenon caused by human beings who burn fossil fuels,  
• Ewhich most scientists agree to be a phenomenon caused by fossil fuels burned by human beings,