What type of optical storage uses a medium wavelength red laser?

The correct answer is that a DVD (Digital Versatile Disc) utilizes a medium wavelength red laser for reading and writing data. DVDs employ a red laser that typically has a wavelength of around 650 nanometers. This wavelength allows DVDs to store data at higher densities than CDs, which use a longer wavelength red laser around 780 nanometers.

In contrast, a CD employs a longer wavelength red laser, making it less efficient in terms of data storage compared to DVDs. Blu-ray Discs, on the other hand, use a blue laser with a much shorter wavelength of approximately 405 nanometers, which enables even greater data storage density than DVDs. Magnetic tapes are a completely different technology that does not utilize lasers at all, as they rely on magnetic media for data storage. The distinguishing feature of DVDs, therefore, is their use of a medium wavelength red laser, enabling enhanced data capacity over older optical storage technologies like CDs.