The correct answer is ssh -X user@hostname as it enables X11 forwarding securely, allowing the graphical output of the remote application to be displayed on the local machine. The -Y option is less secure than -X and should be used with caution as it provides trusted X11 forwarding, which can expose the local system to possible X11 security risks. The -x option disables X11 forwarding and is incorrect. Lastly, the -C option compresses data during the session, which might be useful in low-bandwidth scenarios but does not address the requirement for X11 forwarding and GUI display. Therefore, while -C combined with -X could be used together, -C alone is not correct for the scenario described.