; (ii) a merit system; (iii) a system that measures earnings by quantity or quality of production; or (iv) a differential based on a bona fide factor other than sex, race, or national origin, such as education, training, or experience, except that this clause shall apply only if— (I) the employer demonstrates that— (aa) such factor— (AA) is job-related with respect to the position in question; or (BB) furthers a legitimate business purpose, except that this item shall not apply if the employee demonstrates that an alternative employment practice exists that would serve the same business purpose without producing such differential and that the employer has refused to adopt such alternative practice; and (bb) such factor was actually applied and used reasonably in light of the asserted justification