Please show all the work on how did you get the answer

Blackhawk Inc. has two divisions, North and South, both held to the same corporate required minimum rate of return. For last year, the divisions showed the following performance: North Div South Div Net Operating Income 45,000 22,500 Residual Income 9,000 $ 6,750 Q. Which of the following must be true? A. South Division has a lower ROI and more than half the assets of North Division. B. North Division has a higher ROl but lower assets than South Division. C. North Division has a lower ROI and at least twice as much in operating assets as South Division. D. South Division has a higher ROl and more than twice the operating assets of North Division. E. None of the above are true