The correct answer is C) give him sips of cool water. The key to treating heat exhaustion is to lower the person's body temperature and replace lost fluids. Giving the person sips of cool water is the appropriate first aid measure, as it helps rehydrate the body without overwhelming the system. Artificial respiration (A) is not necessary for heat exhaustion. Putting the person in an ice water bath (B) can be dangerously cold and may trigger shivering, which can further raise the body temperature. Covering with a light cloth (D) may provide some relief, but does not directly address the core issue of dehydration.