High levels of CO2 in the atmosphere have been attributed to the use of fossil fuels and rapid deforestation in Africa, South America and Asia

The fact that 43 percent of people filing income tax returns in 2013 paid no income tax at all is partly explained by the fact that the income tax is __________

a. regressive b. progressive c. proportional d. flat

Secularism in the United States historically has taken the form of ______.

A. state neutrality toward religion B. keeping religion out of the public sphere C. actively supporting religious groups within civil society D. an official state religion