Because metallic mirrors absorb some light, they waste energy. When light strikes a metallic mirror, electrons in the mirror move, using energy and dimming the reflected image. As a result, metallic mirrors cannot be used in applications in which minimizing energy loss is important, such as high-powered lasers. Which one of the following most accurately expresses the argument's main conclusion? ['Part of the light falling on metallic mirrors tends to be absorbed by them.', 'Metallic mirrors are unsuitable for applications where it is crucial to minimize energy loss.', 'High-powered lasers require mirrors that conserve energy.', 'Metallic mirrors reduce the effectiveness of high-powered lasers.']