Today CD-ROMs aren't as popular as pendrives, but a few years ago they were a big step forward in terms of data storage. Its main advantages (especially in comparison to previous tools) are that it can store a lot of information (up to 700 MB) and it's easy to record user's own information. CD-ROMs are also easy in use.
If you need only 1 answer, just pick whichever you like :)