Which of the following types of optical storage media allows users to erase and rewrite data on the disc more than once?

Introduction / Context:
Optical storage media such as compact discs and DVDs come in different formats. Some can be written only once, while others allow data to be erased and rewritten many times. Knowing the difference is important when choosing a disc for backup, file transfer or long term archiving. This question tests your knowledge of which optical disc type supports multiple write and erase cycles, as opposed to those that are read only or write once only.

Given Data / Assumptions:

• We are dealing with optical media, not magnetic disks.
• The focus is on the ability to store data more than once, that is, to erase and rewrite.
• Options include CD-R, CD-RW, CD-ROM, DVD-ROM and Blu-ray ROM discs.
• ROM in a disc name usually indicates read only memory.

Concept / Approach:
CD-RW stands for Compact Disc ReWritable. These discs have a special recording layer that can be changed many times using a compatible CD-RW drive, allowing users to update, erase and rewrite data. In contrast, CD-R (Recordable) discs allow data to be written only once and then behave as read only. CD-ROM, DVD-ROM and Blu-ray ROM discs are pressed at the factory and cannot be altered by the user; they are strictly read only. Therefore, among the options, CD-RW is the only type that clearly supports multiple write cycles on the same disc.

Step-by-Step Solution:

Verification / Alternative check:
Hardware and media packaging clearly label discs as CD-R or CD-RW. CD-RW packaging will state rewritable and often mention the approximate number of rewrite cycles supported. User guides for CD-RW drives describe how to format and erase these discs similarly to a slow removable disk. By contrast, manuals explain that CD-ROM and DVD-ROM drives can only read commercially pressed discs. When burning software presents options, it distinguishes between write once discs (CD-R, DVD-R) and rewritable discs (CD-RW, DVD-RW). These consistent naming practices and behaviours confirm that CD-RW discs meet the requirement in the question.

Why Other Options Are Wrong:

• CD-R discs: Allow data to be recorded only once; users cannot truly erase and reuse them like a rewritable disc.
• DVD-ROM discs: Pressed read only media that users cannot write to; they are used for software distribution and movies.
• CD-ROM discs: Read only compact discs supplied by manufacturers; no user writing is possible.
• Blu-ray ROM discs: High capacity optical discs in read only format, typically used for movies or data distribution, not rewriting by users.

Common Pitfalls:
Students often see the R in CD-R and think it means rewritable, but it actually means recordable, which is normally write once. The RW in CD-RW is the key indicator of rewritable capability. Another confusion arises between ROM and RAM; ROM in disc names firmly indicates read only format. To avoid mistakes, remember: CD-R (record once), CD-RW (rewritable), and ROM means factory written and not user writable.

Final Answer:
The optical media that can be erased and rewritten by users multiple times are CD-RW discs.