Using a privacy screen is a correct practice to prevent shoulder surfing because it narrows the viewing angle of a computer monitor, which minimizes the chance of unauthorized individuals seeing confidential information from a side angle. Changing passwords regularly, while a good security practice, does not prevent shoulder surfing. Using two-factor authentication enhances account security but would not prevent the visual disclosure of on-screen data. Encryption secures data at rest and in transit but does not shield on-screen information from being viewed over the shoulder.