This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to upgrade ubuntu to windows operating system 
Insert the windows installation disc and reboot the system. 
In the boot-up screen, press the key labeled to enter bios, i.e. del, f1 or f10. In the bios, change the boot settings to allow the pc to boot from the optical drive, i.e. cd-rom.

Pick your answer from:
(A). Save the changed bios settings and restart the system. Press the " enter " key to boot from the cd and thereafter press the " f8 " key to accept the terms and conditions to use windows operating system.
(B). Try to overcome your antivirus and virus problems. Once your system is booted up, change the automatic boot options to enable or disable previrus software to ensure it does not crack or crash.
(C). In the pop-up screen, enter windows anti-boot. For example, let's use, ubuntu anti-boot, not geoul anti-boot/pro anti-boot /.
(D). The run dialog box will appear inside. Click " continue " on the bios prompt and select the set of media players (cds) you would like to upgrade to the hardware store.
The answer is:
(A).