CO2 (carbon dioxide), CH4 (methane), and N2O (nitrous oxide) are the three main forms of carbon found in the atmosphere. CO2 is the most abundant and accounts for approximately 95% of the total carbon in the atmosphere. It is released into the atmosphere primarily through human activities such as burning fossil fuels and deforestation. CH4 and N2O are much less abundant than CO2
that means the answer is: Carbon dioxide (CO2)