What is the greenhouse effect?

The greenhouse effect refers to the natural process by which certain gases in the Earth's atmosphere, known as greenhouse gases, trap heat. This process is crucial for maintaining the planet's temperature and supporting life. Sunlight enters the atmosphere, and while some of it is reflected back into space, much is absorbed by the Earth's surface and then re-radiated as infrared energy. Greenhouse gases such as carbon dioxide, methane, and water vapor absorb and re-emit some of this energy, preventing it from escaping back into space. This results in a warming effect that keeps the Earth's average temperature at a level suitable for life. Without the greenhouse effect, the Earth would be significantly colder, making it difficult for many forms of life to survive.

The other options do not accurately describe the greenhouse effect; for instance, growing plants in greenhouses is a agricultural practice, solar radiation affects the Earth's temperature but doesn't involve heat retention in the atmosphere, and energy conservation refers to the principle of conserving energy rather than the physical processes of heat trapping by gases.