The boot process of a laptop is slow and often displays "no operating system found". Which of the following would BEST solve these problems?

Reformatting the MBR is a destructive recovery operation that could erase the partition table and is not appropriate as a first corrective action for a boot ordering problem.

Disabling the CD/DVD drive from boot options removes one unnecessary boot check but does not address other devices that may still precede the HDD, making it an incomplete fix.

When the HDD is not first in the boot sequence, the BIOS/UEFI iterates through all higher-priority devices - such as optical drives, USB ports, or network adapters - before reaching the hard drive, causing the slow boot. If a non-bootable device is checked first, the firmware may report 'no operating system found' before eventually falling through to the correct drive. Placing the HDD at the top of the boot order eliminates unnecessary device polling and ensures the OS loads immediately.

Removing external USB drives during boot addresses one possible incorrect boot device but is a workaround rather than a permanent fix, and does not correct the root cause of improper boot order.