Which sentence in paragraph 1 explains what Americans are doing to help the environment?
 O a. Today, 60 percent of us believe that climate change is a serious threat.
 O b.In 1980, coal, oil and gas made up 89 percent of the energy we used.
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 c. 90 percent of us have recycled in the last year.
 O d. Sometimes you can even find low belief in climate change.