Which of the following is a type of lightning arrestor?

A rod gap is a type of lightning arrestor designed to protect electrical equipment from damage caused by lightning strikes. It works by creating a space that allows the electrical charge from a lightning strike to jump across, directing the high voltage away from sensitive equipment and grounding it safely. This mechanism helps prevent power surges that could otherwise lead to catastrophic failures in the electrical system.

In contrast, transformers, voltage regulators, and capacitors serve different roles within an electrical system. Transformers are primarily used to change the voltage levels in power distribution, voltage regulators maintain a consistent voltage output, and capacitors store and release electrical energy as needed. While all these components are essential for the operation of an electrical grid, they do not serve the function of protecting against lightning. Thus, the rod gap stands out as the correct type of lightning arrestor.