Answer:
D) carbon dioxide
Explanation:
Carbon dioxide (CO2) is the most important greenhouse gas which is known to absorb heat that would otherwise be lost to space. It has been shown that CO2 causes approximately 80% of global warming. Different human activities, but especially the burning of fossil fuels, are the main cause of global warming. It has been estimated that 40 billion metric tons of CO2 produced by human activities are being discharged into the atmosphere annually. Other human activities associated with global warming by increasing the concentration of CO2 in the atmosphere include deforestation and cement production.
