Which class of architectural information held within the Architecture Repository would contain adopted reference models?

The class of architectural information that would contain adopted reference models is the Reference Library. This is because the Reference Library serves as a repository for standard reference materials, templates, patterns, and models that have been recognized and adopted within the context of an enterprise architecture.

Reference models are essentially frameworks that outline best practices or structured guidance that an organization can utilize in their architecture efforts. They are important for ensuring consistency and understanding across different projects and initiatives. This is why they fit perfectly within the scope of a Reference Library, as it organizes and keeps track of such resources for accessibility and use by architects and stakeholders.

On the other hand, while the Architecture Metamodel defines the structure and semantics of the architectural artifacts, it does not specifically contain adopted reference models per se; instead, it outlines how different architecture elements relate to each other. The Architecture Capability focuses on the processes, skills, and roles needed to deliver architecture within the organization, rather than gathering specific reference models. Lastly, the Standards Information Base consists of standards and specifications relevant to the architecture but may not encompass the broader reference models which guide architectural practices.

Thus, the Reference Library is the correct class that specifically deals with adopted reference models within an enterprise architecture framework.