The correct option is CO (Carbon Monoxide).Explanation:Greenhouse Effect: Solar energy is trapped by the earth atmosphere and radiate slowly so to cover our earth with a warm blanket.This is the natural process of the greenhouse effect on earth to maintain its temperature and makes the earth perfect for life.Greenhouse gases are carbon dioxide, other greenhouse gases are methane, water vapour, nitrous oxide, CFCs and ozone. Values of radiation absorbed by the greenhouse gases are as follow:GasValue of absorption in percentageOzone10.2 %Methane16.3 %Carbon Dioxide56.4 %Nitro Oxide 5.4 % From the above table, it is clear that carbon dioxide absorbs the maximum radiation in the earths atmosphereHence the correct option is Carbon Monoxide (CO) which is not a greenhouse gas.The major greenhouse gases areWater vapour - causes about 36% - 70% of the greenhouse effectCarbon dioxide (CO2) causes 9 - 26%Methane (CH4) causes 4 - 9%Ozone (O3)Nitrous OxideChlorofluorocarbons (CFCs)Important PointsGlobal warming: If the number of greenhouse gases crosses by delicate proportion, the natural greenhouse balance may get disturbed and there is a continuous rise in the temperature of the earth by trapping the solar heat continuously.This creates the overall effect of Global warming.