Final answer:
The thermoneutral zone is the range of environmental temperatures where homeothermic metabolic rates are minimal and organisms can maintain a stable internal body temperature without exerting energy for thermoregulation.
Step-by-step explanation:
The range of environmental temperatures within which homeothermic metabolic rates are minimal is called the thermoneutral zone.
This zone is the temperature range in which homeothermic organisms, such as mammals, can maintain a stable internal body temperature without having to exert energy for thermoregulation. In this zone, the metabolic rates are the lowest and there is minimal need for the body to adjust its temperature.