The correct response would be A. The slowest step that determines the speed(rate) of the overall reaction.
Among all the choices given (copper, clay, plastic, and glass), only copper is metal. By being metallic, copper is then able to conduct heat well more than the other materials. This makes it more suitable for the the new equipment composition. Thus, the answer to this item is letter "D. Copper is conductive and will absorb heat to cook the food."
