Which of the following describes a CD-R?

A CD-R, or Compact Disc Recordable, is specifically designed to allow users to write data onto it just once, after which the data cannot be erased or modified. This means that once you burn files onto a CD-R, they are permanently etched onto the disc, making it ideal for distributing files or archiving data that does not need to be changed.

The option that identifies a CD-R accurately details its defining characteristic: the one-time write capability. Other types of optical discs, like CD-RWs (Compact Disc Rewritable), allow for multiple writes and erases, which is not the case with a CD-R. The other choices reference devices or storage formats that do not align with the specific functions or properties of a CD-R, which primarily focuses on its writable nature without erasure. This clarity about the functionality of the CD-R reinforces why this particular description is the correct one.