Which model is characterized by a client-server relationship for database operations?

The two-tier model is characterized by a client-server relationship for database operations. In this model, the client directly communicates with the server to request and manipulate data. The client typically consists of a graphical user interface (GUI) that allows users to interact with the database, while the server handles the data management, including storage, retrieval, and processing. This separation allows for efficient data handling and simplifies the architecture by clearly defining which components are responsible for specific tasks.

In a two-tier architecture, the client application sends queries to the server, which processes these requests and returns the necessary data. This efficiency is particularly advantageous for environments where the load can be balanced between the client application and the server, making it a widely used model for many enterprise applications.

The other models presented do not embody the same direct client-server relationship. The one-tier model typically runs all functions on a single machine without a separation between client and server components. The cloud model involves resources accessed over the internet, which can abstract and distribute tasks differently than a strict client-server approach. The distributed model generally involves multiple interconnected servers sharing the load, deviating from a direct client-server interaction.