How does an electrode type boiler function primarily?

An electrode type boiler functions primarily by heating water through electric elements. This type of boiler uses electrodes immersed in water to conduct electricity, which causes the water to heat up due to the resistance of the water to the electric current. The process is efficient, as it directly heats the water without the need for combustion or external heating elements. The generated steam or hot water can then be used for various applications, such as heating or power generation, depending on the system's design and purpose.

In contrast, other options like generating electricity from steam pressure or heating through the burning of fossil fuels do not apply to the operation of an electrode type boiler, as it relies solely on electrical energy for heating. Thus, the correct answer reflects the unique mechanism by which electrode type boilers operate, distinguishing them from other types of boilers that utilize combustion or different heating methods.