Which backup should I use.

Can someone help un confuse me. I want to know what backup option to choose.
I want to backup windows 10 desktop with one hard disk.

Help says
Entire Computer. Choose this option to back up all storage devices of your PC.
But I think this includes any usb drives and even the backup usb drive I have in the computer. I just want to backup my hard disk that has my files and os.

So I assume ??? that it is this option I want. Eg click on all the hard disks in the system that I want to backup. (I have 1)

Disk/Volumes. Left click an object(s) you’d like to back up. When selecting a volume that hosts
Windows OS you may be warned that the wizard additionally selects another one that contains
boot system files. Though it’s not recommended, you can deselect any volume you consider
unimportant.

Can anyone tell me what they think?

Hello and welcome to the forums!
"Entire Computer" selects all Hard Disks, which don't contain "Removable" flag. In some cases, USB HDD might appear there.
"Disks/Volumes" allow to back up specific Disks (you can exclude your USB HDD from the selection in this case), or specific Partitions.

So, you need to choose "Disks/Volumes" and click on the Hard DIsk (larger ribbon) so that all Partitions will be added to selection.