A thermogram is a representation of infrared electromagnetic waves better known as heat waves. So the correct answer is infrared electromagnetic waves or infrared waves.
Step-by-step explanation:
The thermogram is associated with infrared camera creates a picture by changing effulgent heat into a symbol which will be displayed on a monitor (and later printed). The infrared energy emitted from the associated object is directly proportional to its temperature. Thus it can be used for temperatures that are accurately measured by the infrared camera.