What's the meaning of the `an entire hard disk drive`?
Solution 1:
It means a complete physical drive, as opposed to just individual partitions which themselves contain file systems upon which a user stores files.
You will usually store files within a partition rather than an actual drive. That we call it the "C drive" is a simplification, it is actually the "partition that has been allocated the drive letter C".
They are saying that they will copy all the information on a drive, including partition boundaries, boot sectors and potentially the Host Protected Area (HPA).