The correct answer is: D. All of the above.
XConfigurator, XF86Setup, and xf86config are all X-based tools that are available for configuring the X Window system.
XConfigurator is a graphical tool that can be used to configure the X Window system. It is available for most Linux distributions.
XF86Setup is a text-based tool that can be used to configure the X Window system. It is available for most Linux distributions.
xf86config is a text-based tool that can be used to configure the X Window system. It is available for most Linux distributions.
Each of these tools has its own advantages and disadvantages. XConfigurator is the easiest to use, but it is not as powerful as XF86Setup or xf86config. XF86Setup is more powerful than XConfigurator, but it is not as easy to use. xf86config is the most powerful of the three tools, but it is also the most difficult to use.
The best tool to use depends on your needs and preferences. If you are a beginner, you should use XConfigurator. If you are more experienced, you can use XF86Setup or xf86config.