The correct answer is SAML (Security Assertion Markup Language). SAML is an XML-based standard used for single sign-on (SSO) and identity federation. It allows identity providers (IdPs) to share authentication and authorization data with service providers (SPs), passing secure tokens containing user attributes and credentials.
A). IAM (Identity and Access Management) is the broader framework, not specifically XML-based.
B). MFA enforces multiple factors for authentication but does not involve XML assertions.
C). RADIUS is an AAA protocol, but it uses UDP, not XML assertions.
SAML is widely used in federated identity systems, enabling secure authentication across different domains and applications without requiring multiple credentials.
References (CompTIA Network+ N10-009):
Domain: Network Security - Authentication methods, SAML, SSO.