Final answer:
An isolated system is a system that is completely isolated from its surroundings and does not interact with them. An example of an isolated system is the system shown in Figure 7.15(a).
Step-by-step explanation:
An example of an isolated system is the system shown in Figure 7.15(a). In an isolated system, the net external force is zero, meaning there are no external forces acting on the system. This allows the system to be completely isolated from its surroundings and not interact with them. In the given options, a car's AC system (option A), a mouse on an exercise wheel (option B), and a single cell (option C) are not isolated systems because they interact with their surroundings.