What is a heating system that utilizes resistive heating elements installed in a duct or central furnace?

The correct answer refers to a type of heating system known as a "hot water system," specifically in the context of using resistive heating elements within a duct or central furnace. In this case, while the term "hot water system" is typically associated with water being heated and distributed through pipes, the question highlights the use of resistive heating elements, which convert electrical energy into heat.

These resistive heating elements are often found in specific applications, such as electric furnaces or baseboard heaters within certain systems. They heat air directly, which is then circulated through ducts.

By contrast, the other options do not correctly identify a heating system utilizing resistive elements. A split system generally refers to a type of air conditioning or heat pump system that comprises both indoor and outdoor components but does not specifically rely on resistive heating. A cooling system primarily focuses on reducing temperatures rather than providing heat, and an insulation system relates to insulating components within a structure rather than a method of heating itself. Thus, recognizing the specific role of resistive heating elements clarifies the correct choice regarding heating methods in utility services.