Which feature can be altered by installing a plug-in to the vSphere Web Client?

Installing a plug-in to the vSphere Web Client allows for customization and enhancement of the user interface, which corresponds directly to the feature described in the correct choice. Plug-ins can add new functionalities, alter the appearance of the interface, and improve the overall user experience by integrating additional tools and features into the Web Client.

Plug-ins can provide various functionalities tailored to specific organizational needs, which can include dashboards, monitoring tools, or other extensions, ultimately enabling users to interact more efficiently with their vSphere environment.

In contrast, user authentication methods, network configuration options, and database configuration settings are foundational elements managed through the core administration settings of vSphere and generally do not undergo modifications through plug-ins. These components require separate configurations and management, not influenced by the installation of a plug-in in the Web Client interface.