What serves to determine which ports receive 60/90 alternating current voltage in splitters and directional couplers?

The correct answer is based on the role of plug-in fuses in managing the distribution of voltage to different ports in splitters and directional couplers. Plug-in fuses are designed to protect circuits by breaking the connection when an overload or fault occurs, which helps ensure that the appropriate current flows to designated ports.

In the context of splitters and directional couplers, these devices may utilize plug-in fuses to manage and monitor the distribution of 60/90 alternating current voltage. This ensures that only the correct amount of voltage is directed toward the ports, preventing any potential damage from excessive current flow and facilitating reliable operation.

While other options, such as switching relays, internal resistors, and transformers, contribute to various functions within electrical systems, none specifically relate to the determination of which ports receive the alternating current voltage in the manner that plug-in fuses do. Switching relays may control circuit connections but do not necessarily govern voltage allocation. Internal resistors control current flow but do not direct voltage to specific ports. Transformers are used for voltage conversion rather than for determining voltage distribution among ports. Thus, plug-in fuses serve a unique role in ensuring that the voltage distribution is maintained within safe limits for selected ports in splitters and directional couplers.