The correct answer is: D. Carbon dioxide
Carbon dioxide is a greenhouse gas that traps heat in the atmosphere. This helps to keep the Earth’s temperature at a level that is suitable for life. Without carbon dioxide, the Earth would be too cold for most plants and animals to survive.
Nitrogen is the most abundant gas in the atmosphere, but it does not play a significant role in maintaining atmospheric temperature. Oxygen is also a relatively abundant gas in the atmosphere, but it does not play a significant role in maintaining atmospheric temperature. Argon is the third most abundant gas in the atmosphere, but it does not play a significant role in maintaining atmospheric temperature.
Carbon dioxide is the only gas listed that plays an important role in maintaining atmospheric temperature.