Reducing the emissions of which gas will lead to reducing the greenhouse effect?

Carbon dioxide

Explanation:

The most abundant and most influential greenhouse gas in Earth's atmosphere is the carbon dioxide. This gas has the ability to trap the heat that is reflected from Earth's surface, thus keeping it in the atmosphere. That results in rise of the global temperatures, as the process has an effect similar to that of a greenhouse.

The levels of carbon dioxide in the atmosphere have been steadily on the rise since the Industrial Revolution, with the main reason for it being the human activity. This is why there has been lot of talks, negotiations, and deals between the nations in order to reduce the emissions of carbon dioxide, or even stop them if possible, as the general consensus is that a rapid rise of the global temperatures may have big consequences for the humans.