How can radiators be classified?

Radiators can be classified based on their physical placement and design, and option C accurately reflects this classification by including wall-hung, floor, and window radiators.

Wall-hung radiators are mounted on the wall, which allows for efficient use of space and is often seen in modern heating systems. Floor radiators are typically larger and sit directly on the ground, often used in traditional heating systems where larger surfaces are needed for effective heat distribution. Window radiators are specifically designed to be placed beneath windows, which is a common practice to counteract heat loss from the window area and maintain a more uniform room temperature.

The other options do not correctly reflect the standard classification based on common practices in heating systems. For instance, "legless, ductless and floor" does not encompass the prevalent design categories recognized in radiator classification. Similarly, "window, duct or floor" mixes terms that are not traditionally used to categorize radiators, such as duct, which refers more to ventilation systems than to radiator types. Thus, the terminology in option C is correctly aligned with industry standards for radiator classification.