Which directory contains configuration files used by the X.org and XFree86 applications on a Linux system?

The directory that contains configuration files used by the X.org and XFree86 applications on a Linux system is /etc/X11. This directory is specifically designated for X Window System configuration, which includes important files that control the operation of the graphical interface.

The X Window System, commonly known as X, allows for the graphical display of information on Unix-like operating systems. Within /etc/X11, you'll find configuration files such as xorg.conf or any other specific configuration files related to the X server and its settings. These files are crucial for customizations such as screen resolution, input device settings, and display settings.

In contrast, /etc/x11 is not a standard directory location for these configuration files, which could lead to confusion. The directory /usr/lib/x11 typically contains the binary files and libraries utilized by the X server, not its configuration files. Lastly, /dev/mapper is used for device mapper entries in Linux, primarily related to logical volume management, and has no relevance to X11 or graphical configurations. Thus, the correct directory for X.org and XFree86 configuration files is /etc/X11.