Final answer:
To enable Windows Remote Management on a newly installed Server Core system using PowerShell, the command 'Enable-PSRemoting -Force' should be executed to configure the system to receive remote commands.
Step-by-step explanation:
To enable Windows Remote Management (WinRM) on a newly installed Server Core system using Windows PowerShell, you should execute the following command:
Enable-PSRemoting -Force
This command configures the system to receive PowerShell remote commands that are sent by using the WS-Management technology. The '-Force' parameter is used to suppress all user prompts and assume a 'yes' response to all selections. This allows the command to be executed non-interactively which is useful for scripts or automating the process.
None of the other options provided in the question, such as installing GUI management infrastructure or setting execution policy, will directly enable Windows Remote Management on a Server Core system.