What is the medium used in optical storage systems for reading and recording data ?

Explanation:

Optical storage systems, such as CDs, DVDs, and Blu-ray discs, fundamentally rely on laser light to read and write data. The laser beam interacts with the disc's surface to detect or create microscopic changes that represent data. Options (a), (c), and (d) are not the primary medium used for this purpose in standard optical drives. Thus, (b) is correct.