Fill in the blank with suitable words based on the information of the text.

Humans cannot change the sun's radiation or the Earth's orbit, but they can control the release of (a) _____ gases. Over the last hundred years, the level of carbon dioxide in the atmosphere has increased (b) _____ . The main reason for this rise is the burning of (c) ______ fuels to produce energy for factories, vehicles, homes, and electricity. These fuels are (d) _______ to meet energy demands. As a result, more carbon dioxide is released into the (e) ______ , which increases the greenhouse effect.