Concept:An accessory in computing is an external or removable component that can be used to store and later retrieve information.
Explanation:The question asks for a computer accessory through which stored information can be retrieved.
A hard disk is mostly an internal storage device, not normally called an accessory.
An input device only sends data into the computer, so it does not directly retrieve saved information.
The control unit is part of the processor and is not an accessory.
A floppy disk is a removable, flexible magnetic disk enclosed in a protective casing.
It is an accessory that can be inserted into a drive to read, retrieve, or store data.
Therefore, among the options, the floppy disk best fits the description of an accessory used for retrieving information.
Answer:D. floppy disk