became the world's largest single source of air pollution by the 1990s.
a. auto emissions
b. waste incineration
c. metal smelting
d. chemical emissions

The answer is C. Auto Emissions

Explanation:

In the 1990's cars were the new thing of the time and since they were older models they didn't and couldn't properly dispose of gasoline in a gas form that polluted the air until newer versions came out that consumed less gasoline and produced less pollution.

isaiah 53: 4-6 and   romans 5: 6-8 speak how jesus was pierced for our transgressions,   crushed for our iniquities and that god demonstrates his own love for us in this: while we were still sinners, christ died for us, and by his wounds we are all healed.   psalm 22: 6-7 and   matthew 27: 39-40   correlate basically by the fact that all of the people who didn´t believe in jesus, were telling him that if he was so powerful as he said he was, he should save himself.     matthew 27: 35 and psalm 22: 18 refers about how they divided his clothes among them   and cast lots for his garment. isaiah 53: 8-9 and matthew 27: 57-60 express the process of the burial of jesus. psalm 22: 15-16 and luke 23: 33-34 speak about his crucifiction, the humilliation of being surrounded by sinners, and asking the lord for mercy for humanity. finally in john 19: 33-35   and isaiah 53: 12 speak about the most important prophecy, the testimony of a living god, who resurrected and buried all of our sins and guilt, for all of us. when he was crucified a man saw a sudden flow of blood and water from his wound, and he gived testimony, for all o us to believe, that he poured out his life unto death,   and was numbered with the transgressors.   for he bore the sin of many,   and made intercession for the transgressors.