Correct Answer: Pyrometers

Solution : The correct option is the Pyrometers .

Luminous objects are things like electric bulbs that produce or radiate light on their own. A particular kind of remote-sensing thermometer used to gauge the temperature of far-off objects is called a pyrometer. It is a device that, using the quantity of thermal radiation a surface emits, can be used to determine a surface's temperature from a distance. This procedure is known as pyrometry and radiometry.