Final answer:
The printer is the only option listed that is not a data storage system; it is designed to produce hard copies, not store data. The other options are all used to store digital information.
Step-by-step explanation:
The student's question asks to identify which among the given options is not a data storage system. Three of the options provided—external hard drive, CD, and flash drive—are all devices that are used to store digital data. An external hard drive, as described in reference to Figure 12.1, magnetically encodes information for quick storage and retrieval. CDs, as shown in Figure 30.40, use laser-etched pits to record digital information, which is then read by an infrared laser as the CD spins. Flash drives utilize flash memory to store data electronically. The only option that does not fit the category of a data storage system is the printer, as it is an output device designed to produce hard copies of documents and images, not to store digital data.