How do you navigate to the parent directory in a Linux file system?

To navigate to the parent directory in a Linux file system, using the command cd .. is the correct choice. In Linux and Unix-like operating systems, cd stands for "change directory." The .. symbol specifically refers to the directory one level up in the hierarchy from the current directory, effectively allowing you to move up to the parent directory.

When you execute this command, the shell interprets .. as a reference to the parent directory of your current working directory, making it a fundamental command for navigation in the file system.

The other options do not correctly facilitate navigation to the parent directory. For instance, cd / takes you to the root directory of the file system, cd parent attempts to access a directory named "parent," which may not exist, and cd back is not a valid command for directory navigation in default Linux shells.