Which element in the grounded electrical circuit is not an effective path for ground fault current?

The grounded conductor is the correct choice when identifying an element in a grounded electrical circuit that is not an effective path for ground fault current. A grounded conductor is typically a neutral wire that carries current under normal operation but is not intended to serve as a safety grounding path. In the event of a ground fault, current should flow through the equipment grounding conductor or bonding conductors due to their low impedance path to ground, which ensures that the fault current can effectively trip protective devices.

On the other hand, the earth itself (option C) can serve as a reference point for grounding, but it is not an effective conductor in the context of immediate paths for ground fault current. The earth might disperse energy in fault conditions, but it does not offer a reliable or low-resistance path necessary for safely clearing faults. Therefore, while the other elements in the circuit actively participate in fault current flow to facilitate protection and safety, the earth does not function in the same manner within the context of a fault current pathway.