Final answer:
An electric circuit that powers a load is best described as one where electric current flows from an energy source, through a conductor, to the load, and then back to the energy source in a closed loop.
Step-by-step explanation:
The best description of an electric circuit that powers a load is that electric current flows from an energy source through a conductor to a load and back to the energy source. A simple electric circuit consists of a closed path through which electric current can flow. This path is typically supplied by conducting wires that connect a load, like a light bulb or a resistor, to the terminals of a battery or another type of energy source. The current leaves the positive terminal of the energy source, travels through the conductor to the load where the electrical energy is utilized, and then returns to the negative terminal of the energy source, completing the circuit.