Answer:
They can both be used in an electric circuit.
Step-by-step explanation:
Though conductors and insulators are very different from each other but still they have a similarity that "they can both be used in an electric circuit".
Conductors are the material that allows electricity to flow and insulators have high resistance and do not allow electricity to flow.
Both conductors and insulators are used in an electric circuit as conductor is used in wires, batteries and bulb to flow current while insulators are used in insulation of wire, switches, plugs and etc. Combination of them makes the circuit shock free.
Hence, the correct answer is "They can both be used in an electric circuit."