Which of the following is called heat radiation?

The correct answer is Option (3) → Infrared radiation

NCERT (2026-27):
Infrared Waves – “Infrared waves are produced by hot bodies and molecules. This band lies adjacent to the low-frequency or long-wave length end of the visible spectrum. Infrared waves are sometimes referred to as heat waves. This is because water molecules present in most materials readily absorb infrared waves … After absorption, their thermal motion increases, that is, they heat up and heat their surroundings.”