Which transmission technology uses fixed 53-byte cells to parcel information?

The correct answer is based on the characteristics of Asynchronous Transfer Mode (ATM) technology. ATM is a network technology that uses fixed-size packets known as cells, which are precisely 53 bytes long—48 bytes of payload for carrying data and 5 bytes for the header that contains control information. This fixed-cell structure allows ATM to efficiently manage and switch data across networks, making it suitable for real-time applications like voice and video transmission, where consistent timing and lower latency are crucial.

In contrast, the other listed technologies employ different methods for data transmission. For instance, ISDN (Integrated Services Digital Network) typically transmits information in variable-length packets and supports circuit-switched and packet-switched connections primarily for voice and data. Frame relay is another packet-switched technology, but it uses variable-length frames rather than fixed-size cells, allowing for more flexible data handling. DSL (Digital Subscriber Line) is a technology primarily used for providing internet access over telephone lines and relies on a different method of data packetization.