Final answer:
The correct answer is B) CO₂ levels increased significantly from 1850 to 2015, due to the burning of fossil fuels leading to unprecedented rises in atmospheric CO₂.
Step-by-step explanation:
The question about carbon dioxide levels refers to changes in atmospheric CO₂ concentration over a period from 1850 to 2015. The correct answer to the question is B) CO₂ levels increased significantly. The Overview section of the virtual lab states that although atmospheric carbon dioxide levels have historically fluctuated between 180 and 300 parts per million (ppm), the burning of fossil fuels in recent history has caused an unprecedented rise in CO₂ levels beyond the historical maximum. Figures and data provided indicate that over the past 50 years, there has been a steep incline in CO₂ levels, reaching concentrations never before seen in human history, with current levels rising rapidly in just a few hundred years compared to the naturally occurring cycles that took tens of thousands of years.
Scientists attribute this increase mostly to the burning of fossil fuels, which has added CO₂ to the atmosphere at a rate and magnitude much greater than any natural process recorded in the past. This rapid rise in greenhouse gas levels is expected to have a significant impact on climate change and biodiversity within the current century.