5) Plot the cost-effectiveness frontier (CEF) for the following four hypothetical options for someone with back pain. Plot the cost on the x-axis and the pain-reduction units (PRUs) on the Y-axis. Also, calculate the ICER between cortisone injections and a chair cushion: Treatment regimen Total Cost Pain Reduction Do nothing SO 0 units Chair cushion $100 20 units Cortisone injections $700 25 units Acupuncture $1,000 50 units