Thermodynamics

The Sun emits a wide range of electromagnetic radiation, including visible light, ultraviolet (UV) rays, infrared rays, and others. However, infrared rays are the primary radiation that contributes to the Earth's warmth.
- Infrared rays are absorbed by the Earth and re-radiated as heat, which is responsible for maintaining the Earth's temperature. This is often referred to as the greenhouse effect.
- While visible light contributes to illumination, and UV rays have other effects such as causing sunburns, it is the infrared radiation that plays a key role in heating the Earth's surface and atmosphere. Thus, the correct answer is option (A), Infrared rays.