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

The main source of air pollution is the burning of fossil fuels by industries and vehicles. Burning fuel gives off gasses that are poisonous that can damage people’s health. Acidic chemicals in air pollution also combine with precipitation to form acid rain. Acid rain eats away at the surfaces of buildings, kills fish, and can destroy entire forests.

i believe your answer is d)

on the morning of  july 21,  1861, general mcdowell ordered the  unionarmy to attack. it was on this hill that  confederate  colonel thomas jackson and his forces held back theunion  troops.