Mankind's use of renewable energy will lessen the effects of human activities on climate change.

What percentage of Canada's surface freshwater is contained in the Great Lakes? 

A)  about 30% 
B)  about 50% 
C)  about 70% 
D)  about 90%

Which organisms are least likely to be killed by heavy oil components? 

A)  crabs 
B)  clams 
C)  marine birds 
D)  oysters

What was probably NOT a characteristic of the first agricultural communities? 

A)  slash-and-burn cultivation 
B)  specialized farming of one crop 
C)  subsistence agriculture 
D)  shifting cultivation

According to the graphs,before 150 000 years ago,when did the Earth have a high average surface temperature?

Which of the following is an appropriate method of land-use control? 

A)  subsidizing of farmers who use marginal land that is highly susceptible to erosion 
B)  providing tax breaks for owners to develop open space 
C)  developing existing open space 
D)  implementing conservation easements

Carrying capacity is maximum number of a given species that can be sustained in an area without degrading the environment.