The correct answer is D. All of the above.
Horn gaps, rod gaps, and surge absorbers are all devices that may be used to provide protection against lightning overvoltages.
Horn gaps are a type of spark gap that is used to protect electrical equipment from lightning strikes. They work by creating a spark when the voltage between the two conductors reaches a certain level. This spark diverts the lightning strike away from the equipment, protecting it from damage.
Rod gaps are similar to horn gaps, but they use a rod instead of a horn to create the spark. They are often used in conjunction with lightning rods to protect tall buildings and other structures from lightning strikes.
Surge absorbers are devices that are used to protect electrical equipment from voltage spikes. They work by absorbing the excess voltage and preventing it from damaging the equipment. Surge absorbers are often used in conjunction with other lightning protection devices, such as horn gaps and rod gaps.
All of these devices are effective in protecting electrical equipment from lightning strikes. The best type of device to use will depend on the specific application.