What Is the Evidence That Human Activity Is Causing Increased

What is the evidence that human activity is causing increased atmospheric CO₂ levels?

A) The isotopic composition of atmospheric CO₂ can be measured and shows that CO₂ being added to the air now comes from combustion of fossil fuels.
B) There is a correlation between the increase of overall CO₂ levels and human activity since the Industrial Revolution.
C) There is no direct evidence; CO₂ levels fluctuate naturally and it may just be coincidence that higher CO₂ levels correspond to this period of human activity.
D) There is no direct evidence; it is impossible to know what CO₂ levels were like in the past, so there is no standard for comparison.
E) Since forests are being cut down by humans, CO₂ levels must be rising because there are fewer plants that remove CO₂ through photosynthesis.