Final answer:
The SFC (System File Checker) command is the most likely to resolve the issue of a browser not opening by scanning and restoring corrupted or missing Windows system files.
Step-by-step explanation:
When a user cannot open a browser on their system, there are various potential causes for this issue. However, based on the provided commands, the one that is designed specifically to correct issues related to Windows system files would be the System File Checker command, or SFC. This utility scans for and restores corrupted or missing Windows system files.
The command FIXMBR is used to fix the master boot record of the system, bootrec is involved in the repair of the boot configuration data and the system's ability to boot, and RD (remove directory) is a command that would delete a directory and it is not related to resolving browser issues.
To run the System File Checker, the user would need to open the command prompt with administrative privileges and input the following command:
Once the command is executed, the SFC utility will begin scanning and fixing any system file issues that might be preventing the browser from opening.