Answer: Greenhouse
Notes: A greenhouse gas is defined as any gaseous compound that is capable of absorbing infrared radiation thereby trapping and holding heat in the atmosphere. Many greenhouse gases occur naturally in the atmosphere, such as carbon dioxide, methane, water vapor, and nitrous oxide, while others are synthetic. Those that are man-made include the chlorofluoro-carbons (CFCs), hydrofluoro-carbons (HFCs) and Perfluoro-carbons (PFCs), as well as sulfur hexafluoride (SF6).
