Two computer companies, Garnet and Renco

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?

A. Early treatment of high cholesterol does not eliminate the possibility of a stroke later in life.
B. People often obtain early treatment for high cholesterol on their own.
C. Garnet hires a significant number of former employees of Renco.
D. Renco and Garnet have approximately the same number of employees.
E. Renco employees are not, on average, significantly younger than Garnet employees.
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OA: C

Hi.

I do not understand the link between "Renco employees generally remain with Renco only for a few years" and "Salcor lacks any financial incentive".

Does this mean if Renco employees leave the company before they suffer stroke, Salcor will not have to pay for the employees treatment? Is that why the agency has no financial incentive?

Is the link a common knowledge or an inference we could get from the stimulus?

Thank you.