On a Linux device, which of the following commands will start the Nessus client in the background so that the Nessus server can be configured?

'nessus +' is not valid Linux shell syntax and is not recognized as a flag or operator by the Nessus client or the shell.

'nessus *s' uses the glob wildcard character * which has no meaning as a Nessus flag and would be misinterpreted by the shell.

The & shell operator instructs the Linux shell to launch the preceding command as a background process, detaching it from the foreground terminal session. Running 'nessus &' starts the Nessus client in the background so the user can then interact with or configure the Nessus server from the same terminal without waiting for the client process to exit.

'nessus -d' is not the standard option for backgrounding the process in the shell; -d may refer to debug or daemon modes in some tools but does not use the shell's background execution mechanism.