According to An Inconvenient Truth, what is the role of infrared radiation in global warming?

All of the sun's energy is converted to infrared radiation and then remains in the atmosphere. This warms the atmosphere

Over time, infrared radiation makes the atmosphere thinner. This warms the atmosphere

Greenhouse gases trap some infrared radiation in the atmosphere. This warms the atmosphere

The correct answer is greenhouse gases trap some infrared radiation in the atmosphere, causing the warming of the Earth's atmosphere.