Which gas is increasing the most in the atmosphere and causing the biggest threat to the world by intensifying the greenhouse effect?

A) carbon dioxide
B) carbon monoxide
C) ozone
D) fluorocarbon
E) oxygen

Carbon dioxide is the gas that is increasing the most in the atmosphere due to human activities such as burning fossil fuels, deforestation and land use changes. It is a greenhouse gas that traps heat in the atmosphere, leading to global warming and climate change which poses the biggest threat to the world.