What can the plastic on the acrylic mirror be used for?

The choice that indicates the plastic on the acrylic mirror can be used as tinder is correct because acrylic is a type of plastic that can be flammable. In survival scenarios, tinder refers to materials that ignite easily and can be used to start a fire. When acrylic is shredded or turned into small pieces, it can catch a spark or flame quite easily, making it effective for starting a fire in outdoor settings.

This practical usage of acrylic aligns with its properties, as many plastics, when formed into thin, small strips or shavings, can serve as a good fire-starting material when combined with other natural tinder sources. In contrast, the other options do not relate appropriately to the properties of acrylic; it does not serve as a signal, a cutting tool in any functional way, or particularly as a cleaning agent.