Which of the following, if true, most threatens the author's conclusion? A. The initial cost of manufacturing a Dvorak keyboard will be more expensive than that of a QWERTY keyboard. B. Many who have attempted using a Dvorak keyboard claim that learning the configuration of keys takes weeks. C. Those suffering from repetitive stress injuries often attribute the injuries to multiple factors. D. Businesses that have educated employees on the benefits of the Dvorak keyboard have found that employees continue to use the QWERTY keyboard. E. Businesses have found that many employees who believe the QWERTY keyboard is responsible for stress-induced injuries are unaware of the Dvorak keyboard.