How does the Earth absorb and emit electromagnetic radiation?

The Earth absorbs and emits electromagnetic radiation primarily through the interaction of sunlight with its surface. The correct answer highlights that the Earth absorbs most of the short-wavelength radiation that comes from the Sun, which includes visible light and ultraviolet radiation. This absorption occurs because the Earth's surface is made up of various materials that efficiently take in this energy.

Once the Earth absorbs this short-wavelength radiation, it re-emits energy in the form of longer-wavelength infrared radiation. This process is essential for maintaining the Earth's energy balance and supports life by regulating temperatures. The greenhouse effect, where certain gases in the atmosphere trap some of this re-emitted radiation, further illustrates how energy is retained within the Earth's climate system.

The other choices misrepresent how the Earth interacts with electromagnetic radiation. For instance, reflecting all incoming radiation back into space would not allow for the absorption necessary for warming the planet. Only absorbing longer wavelength infrared radiation neglects the critical role of incoming short-wavelength sunlight. Lastly, emitting radiation without any absorption contradicts the fundamental principle of energy conservation, as energy cannot simply be emitted without first being absorbed. Thus, choice B accurately describes the process of energy absorption and emission by the Earth.