Two computer companies, Garnet and Renco, each pay Salcor to provide health insurance for their employees. Because early treatment of high cholesterol can prevent strokes that would otherwise occur several years later, Salcor encourages Garnet employees to have their cholesterol levels tested and to obtain early treatment for high cholesterol. Renco employees generally remain with Renco only for a few years, however. Therefore, Salcor lacks any financial incentive to provide similar encouragement to Renco employees.
Which of the following, if true, most seriously weakens the argument?