The correct answer is D. All of the above.
Static capacitors are used to improve power factor by providing reactive power to the system. This can be done by connecting the capacitors in parallel with the load. The capacitors will then absorb the reactive power that is being generated by the load, which will improve the power factor.
Static capacitors have a number of advantages over other types of power factor correction devices. They are relatively inexpensive, have low maintenance costs, and are easy to install. They also have low losses, which means that they do not consume a lot of power.
Static capacitors are a cost-effective way to improve power factor. They are easy to install and maintain, and they have low losses.