Final answer:
Hard Disk Drives (HDDs) use a magnetic medium for data storage, working through giant magnetoresistance, a nanotechnology that detects changes in electrical resistance caused by a magnetic field. Other mentioned devices like SSDs, USB Flash Drives, CDs, and Blu-ray Discs do not use magnetic storage.
Step-by-step explanation:
The two storage devices that use a magnetic medium for storing data are Hard Disk Drives (HDDs) and tapes (not listed in the options provided, but commonly known to use magnetic storage). HDDs work by magnetically encoding information onto a spinning disk with a read/write head (Figure 12.28). The HDD utilizes magnetism to store digital data in a series of 0s and 1s.
On the other hand, Solid State Drives (SSD), USB Flash Drives, Compact Discs (CDs), and Blu-ray Discs (BD) do not use magnetism for storing data. SSDs store data through interconnected flash memory chips, USB Flash Drives also use flash storage, CDs and Blu-ray Discs use optical storage technology, where data is read and written using lasers to detect pits and lands on the surface of the disc.
In summary, HDDs represent an application of nanotechnology known as giant magnetoresistance, where changes in resistance due to an applied magnetic field are used to read data.