Which of these is an optical medium of storage?

Blu-ray discs are categorized as an optical medium of storage because they utilize lasers to read and write data. Optical storage media typically involve the use of light—specifically, lasers to reflect off the surface of a disc to read the encoded data. Blu-ray discs, for instance, use a blue-violet laser, which allows them to store significantly more data than standard DVDs, which use a red laser. This characteristic of optical storage makes it distinct compared to other types of storage such as flash drives, solid-state drives, and magnetic tape.

Flash drives and solid-state drives are examples of solid-state storage media that rely on flash memory technology, while magnetic tape is a form of magnetic storage that uses magnetization to encode information. Each of these storage methods has its own advantages and use cases, but they do not classify as optical media like Blu-ray discs do.