Which of the following is a simple option to deter attackers who have physical access to a Linux system from performing a root account takeover?

Configuring a GRUB bootloader password requires authentication before boot options can be edited or single-user mode can be accessed. This prevents an attacker with physical access from booting into a recovery shell or changing kernel parameters to gain root access without knowing the password.

Removing the root user from a Linux system is not feasible or recommended, as the root user is essential for system administration tasks.

While a Hardware Security Module (HSM) enhances security, it is a complex and expensive solution, not a 'simple option' to deter physical root takeover.

Disabling single-user mode runlevel can make system recovery difficult and might not completely prevent other methods of root access if the bootloader itself is unprotected.