Which of the following is part of an electrical heating system?

In an electrical heating system, a resistor plays a crucial role as it converts electrical energy into heat through the process of resistance. When electric current passes through a resistor, it generates heat due to its resistance to the flow of electricity. This heat can then be used to warm the space, making resistors an essential component in various electrical heating applications, such as baseboard heaters and electric furnaces.

While other components like a furnace, condenser, and air handler may be part of different types of heating systems, they do not specifically denote an electrical heating system's functionality in the same way that resistors do. A furnace, for example, primarily refers to a heating unit that can work with different fuel sources, while a condenser is more associated with cooling systems, particularly in air conditioning units. An air handler is a device that circulates air but does not directly heat it through electrical means. This distinction emphasizes why the resistor is the correct answer in the context of an electrical heating system.