Which type of radiation is absorbed by the Earth's surface and then re-emitted into the atmosphere?

Infrared radiation is the correct choice because it is the type of radiation that is primarily absorbed by the Earth's surface. When sunlight reaches the Earth's surface, it includes a range of electromagnetic radiation, with a significant portion being infrared. This radiation warms the surface and, in response, the Earth re-emits energy in the form of infrared radiation back into the atmosphere.

This process is fundamental to the greenhouse effect, where certain gases in the atmosphere absorb and re-radiate infrared radiation, thus helping to maintain the Earth's temperature.

In contrast, ultraviolet radiation does not have the same absorption and re-emission process at the Earth's surface as infrared does. X-rays and gamma rays have much higher energy and are not typically associated with the warming of the Earth's surface nor the processes that contribute to atmospheric heating. These higher-energy forms of radiation are absorbed by the atmosphere at various altitudes and do not contribute to the re-emission process that characterizes infrared radiation.