Multiple Choice
According to this graph of changes in Earth's atmosphere, which change took place between the years 1800 and 2000?
A) Nitrous oxide (N2O) levels increased from 270 ppb to 390 ppb.
B) Carbon dioxide (CO2) levels increased from 950 ppb to 1,800 ppb.
C) Carbon dioxide (CO2) levels increased from 290 ppm to 380 ppm.
D) Methane (CH4) levels increased from 270 ppm to almost 2,000 ppm.
Correct Answer:

Verified
Correct Answer:
Verified
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