Approximately what portion of the world's population lives in countries that suffer from ...

Approximately what portion of the world's population lives in countries that suffer from moderate-to-high water stress?
 
  A. One tenth
  B. One eighth
  C. One fifth
  D. One third
  E. One half

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Which of the following is the most complex of all ecosystems?
 
  A. Forests
  B. Oceans
  C. Tundra
  D. Mountains
  E. Deserts

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The earth's temperature would need to rise ___ degrees in order to be considered catastrophic climate change.
 
  A. 1
  B. 2
  C. 3
  D. 4
  E. 5

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The ozone hole was first discovered in the:
 
  A. 1960s
  B. 1970s
  C. 1980s
  D. 1990s
  E. 21st century.

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Which of the following has caused the most pressure on land resources?
 
  A. Urbanization
  B. Population growth
  C. Industrialization
  D. Pollution
  E. Food production