Which of the following authentication methods would be most suitable for Samantha, who is seeking an authentication approach that incorporates the X.509 standard and enables digital signature authentication?

Digital certificates use the X.509 standard (or the PGP standard) and allow the user to digitally sign authentication requests. OAuth allows an end user’s account information to be used by third-party services, without exposing the user’s password. It does not use digital certificates or support digital signing. Kerberos does not use digital certificates, nor does it support digital signing. Smartcards can contain digital certificates but don’t necessarily have to have them.