Which command is used to fix a corrupted boot configuration in Windows?

The command used to fix a corrupted boot configuration in Windows is indeed bootrec /rebuildbcd. This command is a part of the Windows Recovery Environment and is specifically designed to repair issues related to the boot configuration data (BCD), which is essential for the operating system to boot properly. When the BCD is corrupted or missing, the computer may fail to start, and using this command can help rebuild the BCD from scratch, allowing Windows to boot successfully again.

The other options serve different purposes: msconfig is used for configuring system startup options and managing services and startup programs; diskpart is a command-line tool for managing hard drives and partitions, but it does not address boot configuration issues directly; chkdsk is used to check the integrity of disks and can fix file system errors, but it does not specifically deal with the boot configuration data.