4. The following data are available for the CORP, Inc. and the single product it makes Unit selling price .......... $20 Variable Cost per unit.................. $12 Annual Fixed Cost....................... $280,000 Average Operating Assets........ $1,500,000 How many units must the CORP sell each year to have an ROI of 15%? a) 63,125 units b) 11,250 units c) 25,250 units d) 31,175 units e) 45, 750 units