Read the excerpt from "Climate Change: An Overview.”By the early twentieth century, carbon emissions from fossil-fuel burning reached 1 billion tons a year. Automobiles, airplanes, and domestic and agricultural energy demands all contributed to the rising trend. In the 1950s, scientists used a new generation of equipment to confirm that carbon-dioxide concentrations were doubling and that this would have the effect of increased temperatures.
Answer
A
the increase in automobile usage from the early twentieth century through the 1950s
B
the changes in carbon dioxide emissions from the early twentieth century through the 1950s
C
the development of new technologies from the early twentieth century through the 1950s
D
the changes in popular modes of transportation from the early twentieth century through the 1950s