Which technology uses long wavelengths to read data?

The correct answer is based on the differences in technology used by optical media types. Compact Discs (CDs) utilize a laser that operates at a longer wavelength compared to DVDs and Blu-ray Discs. Specifically, CDs use a wavelength of about 780 nanometers, which is in the infrared spectrum, while DVDs use a shorter wavelength of around 650 nanometers (red laser), and Blu-ray Discs utilize an even shorter wavelength of approximately 405 nanometers (blue laser). This use of longer wavelengths in CDs allows for lower data density compared to the more advanced technologies used in DVDs and Blu-ray Discs, which can store more information due to the shorter wavelengths they employ.

In contrast, both DVDs and Blu-ray Discs have greater data storage capabilities because they can read smaller pits on the disc's surface, thanks to the shorter wavelengths of their read lasers. Flash drives, on the other hand, do not use laser technology at all; they rely on solid-state memory to store data. Thus, the technology that uses the longest wavelength for reading data among the choices is the Compact Disc.