What percentage of the world's commercial energy is consumed by the United States,although it has only about 5% of the world's population? 

A)  about 54% 
B)  about 44% 
C)  about 34% 
D)  about 18%

What is the most logical way to cope with the limitations imposed by the three basic physical laws that govern matter? 

A)  Increase the output of low-quality heat. 
B)  Shift to non-polluting nuclear fusion power. 
C)  Increase the input of high-quality energy. 
D)  Use and waste less energy and matter.

Energy flow can be used to diagram the ecological interdependence of species.

What was the cause of flooding in the 1993 upper Mississippi River flood?

A) Heavy snowmelt in Canada sent large volumes of water down the river in the spring.
B) A dam failed because it had been built in a risky place near a fault.
C) Persistent thunderstorms caused large amounts of rainfall over a several-state region.
D) Winter produced rain that melted snow that was on the ground.