Which one of the following reference building blocks is not part of the Solutions Continuum?

The correct reference building block that is not part of the Solutions Continuum is systems libraries. The Solutions Continuum is a framework in TOGAF that categorizes solutions based on their level of generality, ranging from generic to organization-specific solutions. The main components of the Solutions Continuum include foundation solutions, common systems solutions, and organization-specific solutions.

Foundation solutions refer to the fundamental architecture components that provide a basis for building systems. Common systems solutions are more tailored and involve shared functionalities that can be reused across different applications or organizations. On the other hand, organization-specific solutions are tailored solutions that address the unique needs and requirements of a specific organization.

Systems libraries, however, do not fit within this continuum as they generally refer to repositories or collections of components, code, or shared resources used in a variety of applications but do not themselves represent a distinct level of architectural solution as defined in the Solutions Continuum.