The BEST method of maintaining the confidentiality of digital information is using access controls, file permissions, and encryption. This is because these techniques help to prevent unauthorized access, disclosure, or modification of digital information, by restricting who can access the information, what they can do with it, and how they can access it. The other options are not as effective as using access controls, file permissions, and encryption, because they either relate to protecting availability (B), integrity C, or awareness (D).