Which of the following describe characteristics of the controlled group rules that apply to qualified retirement plans? I. If a controlled group exists, the employees of all related organizations must be considered in determining if the plan satisfies statutory coverage and eligibility requirements. II. A controlled group of corporations is not permitted to provide a qualified retirement plan. III. One type of controlled group relationship is the parent-subsidiary relationship, reflecting ownership between corporations. IV. One type of controlled group relationship is the brother sister relationship, reflecting individuals' common ownership of corporations. I and II only I and III only II and III only II and IV only I, III, and IV only