Which of the following is an example of a spooled device?
The terminal used to enter the input data for the C program being executed
An output device used to print the output of a number of jobs
The secondary memory device in a virtual storage system
The swapping area on a disk used by the swapper
Answer is (B).
spooling(simultaneous peripheral operations online) is a technique in which an intermediate device such as disk is interposed between process and low speed i/o device.for ex. in printer if a process attempt to print a document but printer is busy printing another document ,the process,instead of waiting for printer to become available,write its output to disk.when the printer become available the data on disk is printed.spooling allows process to request operation from peripheral device without requiring that the device be ready to service the request.
Refer to the second answer in the link above.