What is the main source of air pollution in the world today?

a. nuclear power plants
b. carbon emissions from cars and trucks
c. chemical waste from industrial centers
d. coal-burning factories

What event brought the us into wwii? what conflicts happened after the us entered the war? i know the first part of this question, i need with the second part.

From the soviet point of view, which reagan policy most threatened to create a new arms race? a. strategic defense initiative b. u.s. support for israel c. aid to the anti-soviet rebels in afghanistan d. iran-contra scandal

What refers to the division of power among the three branches of government