Which of the following commands makes /bin/foo executable by everyone but writable only by its owner?

The clause u=rwx explicitly sets owner permissions to read, write, and execute. The clause go=rx sets both group and others to read and execute only, denying write access to non-owners. Together these produce the 755 (rwxr-xr-x) bit pattern, satisfying both requirements.

The token o+rwx adds write permission to the others class, which directly violates the requirement that only the owner may write to the file.

Octal 577 translates to r-x/rwx/rwx, which denies write permission to the owner while granting it to both group and others - the opposite of the stated requirement.

Octal 775 translates to rwx/rwx/r-x, which grants write permission to the group in addition to the owner, violating the writable-only-by-owner constraint.