The correct answer is: C. either (A) or (B).
Synchronous capacitors can be installed at either the receiving end or the sending end of a distribution system to improve power factor. The location of the capacitors will depend on a number of factors, including the system voltage, the load characteristics, and the desired improvement in power factor.
In general, capacitors installed at the receiving end will have a greater impact on power factor than capacitors installed at the sending end. This is because the receiving end is where the load is located, and the capacitors will help to reduce the reactive power that is drawn by the load.
However, there are some cases where capacitors installed at the sending end may be more beneficial. For example, if the system voltage is high, then capacitors installed at the sending end can help to reduce the voltage drop in the system. Additionally, if the load is highly inductive, then capacitors installed at the sending end can help to improve the power factor without having to install as much reactive power at the receiving end.
Ultimately, the best location for capacitors to improve power factor will depend on the specific characteristics of the distribution system.