Which identity system allows multiple organizations access to a shared NoSQL database?

The correct choice, which is federations, is particularly suited for scenarios where multiple organizations need to access a shared resource like a NoSQL database. Federated identity management establishes a framework that allows users from one organization to use their credentials to access resources in another organization. This is crucial in collaborative environments where data sharing among different entities is needed, enabling seamless access without requiring each organization to create and manage separate accounts for users from other organizations.

In the context of a shared NoSQL database, which often requires real-time interaction and data access among different organizations, a federation provides the necessary trust between the different identity providers and allows for an efficient and secure method for authentication and authorization. By employing federated identities, organizations can streamline user access while maintaining security protocols.

Other identity management systems such as single sign-on streamline user login processes but typically do not encompass cross-organizational access in the way that federations do. LDAP primarily serves as a protocol for directory services and is less about multi-organization access. An authorization manager focuses more on granting permissions rather than managing identity across several organizations. Hence, federations emerge as the most appropriate solution for enabling shared access to resources like a NoSQL database among multiple organizations.