According to best practices, which of the following should be the FIRST step after a full boot into a newly installed Windows Server OS?

Removing the Internet Explorer Enhanced Security configuration often reduces the server's security posture and is typically performed later, if at all, based on specific application requirements, not as an initial security best practice.

While disabling the Guest account is a good security practice, on modern Windows Server installations, it is often disabled by default, and patching against systemic vulnerabilities takes precedence over user account management as the immediate first step.

Apportioning additional storage is a system configuration task related to resource allocation, which, while important, is not a foundational security or stability measure that should precede patching a newly installed OS.

Applying all relevant updates and patches is crucial as the first step after installing a new Windows Server OS to address known security vulnerabilities and bugs. This proactive measure ensures the system is secured against threats that may have emerged since the OS release or last update.