SAML (Security Assertion Markup Language) is an open standard for exchanging authentication and authorization data between parties, particularly in the context of single sign-on (SSO). It is based on XML and is widely used to enable secure web-based authentication and authorization across different domains. The correct full form is Security Assertion Markup Language, where 'Assertion' refers to statements about a subject (e.g., identity, attributes), 'Markup' indicates the XML-based structure, and 'Language' denotes the defined syntax.

Option A ('Security Assertion Markup Language'): This is the correct and official full form of SAML as defined by OASIS (Organization for the Advancement of Structured Information Standards).

Option B ('Security Authorization Markup Language'): Incorrect, as 'Authorization' is not part of the acronym; SAML focuses on both authentication and authorization assertions.

Option C ('Security Assertion Management Language'): Incorrect, as 'Management' is not part of the acronym; SAML is about markup, not management.

Option D ('Secure Authentication Markup Language'): Incorrect, as 'Secure' is not part of the acronym, and SAML covers more than just authentication.

The correct answer is A, aligning with the CAP syllabus under 'Authentication and Authorization' and 'Single Sign-On (SSO) Standards.'