What optical media can use two layers to write 8.5 GB of data?

The correct choice is the format that uses two layers to write 8.5 GB of data, which is optical media known as DVD-9. This type of DVD is designed with a dual-layer structure, allowing for approximately 8.5 gigabytes of storage without significantly increasing the physical size of the disc. Each layer can be accessed independently, effectively doubling the storage capacity compared to standard single-layer DVDs.

DVD-9 discs are commonly used for video content, such as movies, because they can hold a considerable amount of data in a high-quality format. This capacity makes them a popular choice for commercial DVD video releases.

The other formats listed do not match this capacity; for example, DVD-R is typically a single-layer disc with a maximum capacity of 4.7 GB, while CD-RW and Blu-Ray discs have different characteristics and capacities. CD-RW, primarily designed for rewriting data, offers up to 700 MB, which is far below the capacity of DVD-9. Blu-Ray discs, although they hold significantly more data, typically offer capacities of 25 GB for single-layer and 50 GB for dual-layer, making them separate from the DVD standard.