Answer:
d. carbon dioxide
Explanation:
The human activities contribute to lot of emissions of numerous different gasses into the atmosphere. The gasses that are released the most though are the greenhouse gasses, especially carbon dioxide.
The reason why the carbon dioxide is the gas that is added the most to the atmosphere by the humans is because the humans use fossil fuels. The fossil fuels run the economies around the world, so they are crucial to the industry, but also for the transportation, and travelling, being also used more and more in the agriculture too.
When the fossil fuels are burned they release carbon dioxide, as their basic component is carbon, so when they burn the carbon interacts with oxygen and creates lot of carbon dioxide.
The result of this is contributing to the global warming, as the more greenhouse gasses there are, the higher the temperatures become on global level.
