List and briefly explain two other discovery / inventions that were necessary for the eventual development of the technology needed to create and listen to cds

CD's use laser beams to read a pattern, so the invention of the laser is necessary.

CD's use digital representation of audio, so the invention of the analog-to-digital converter (for recording) and the digital-to-analog converter (for playback) was needed as well.

Is this a statement or question?

Kpa - known-plaintext attack