Explanation
Running a command in the background of your shell means that the command will execute asynchronously, without blocking the shell prompt or waiting for user input. This can be useful for commands that take a long time to complete, or that do not require user interaction. One of the valid reasons to run a command in the background is when the command has to run immediately but the user needs to log out. For example, if the user wants to start a backup process that will take several hours, but also wants to close the terminal session and log out from the system, they can run the backup command in the background by appending an ampersand (&) to the command line. This way, the backup command will continue to run even after the user logs out, and the user can check the status or output of the command later. The other options are either incorrect or not applicable. Running a command in the background does not affect the execution priority of the command, which is determined by the nice value and the scheduler. Running a command in the background does not delay the execution of the command, which will start as soon as possible. Running a command in the background does not guarantee that the command will survive a system shutdown or reboot, unless the command is configured to do so with a service manager or a startup script. References:
* LPIC-1 Exam 101 Objectives, Topic 103: GNU and Unix Commands, 103.1 Work on the command line
* LPIC-1 Linux Administrator 101-500 Exam FAQ, LPIC-1 Exam 101 Objectives, GNU and Unix Commands (Total Weight: 25)