Final answer:
Among copper, aluminum, glass, and Styrofoam, Styrofoam is the best heat insulator due to its structure that incorporates many small pockets of air, leveraging air's low thermal conductivity.
Step-by-step explanation:
When considering the options given for the best heat insulator, we can deduce that Styrofoam is the best choice among the four. Metals like copper, gold, and aluminum are excellent heat conductors due to their high density of free electrons, which allows them to transfer heat quickly. This makes them poor insulators. Glass, being less conductive than metals, still conducts heat faster than materials that are considered good insulators. Styrofoam, on the other hand, is composed of polystyrene foam that incorporates many small pockets of air. Air has very low thermal conductivity, which means that it is a poor conductor of heat and thus makes Styrofoam an excellent insulator. This principle is shared among other good insulators like fiberglass, wool, and goose-down feathers, all of which use air pockets to their advantage to slow down the transffer.