A systems administrator has uninstalled all but the minimum required services on a VM. This is an example of:

Hardening a VM involves implementing security measures to reduce its attack surface and vulnerability to threats. Uninstalling all but the minimum required services directly contributes to hardening by removing unnecessary software components that could potentially be exploited, thereby minimizing potential entry points for attackers.

Patching refers to applying updates or fixes to software, typically to address bugs or security vulnerabilities, rather than the complete removal of non-essential services.

Role-based administration (RBA) is a security concept where access permissions are granted based on a user's role, not a method for securing a system by uninstalling services.

Federation involves establishing trust relationships between different identity providers or systems to enable single sign-on or shared resource access, which is unrelated to the process of securing a single VM by removing services.