The correct answer is C. Virtual memory is a technique that uses secondary storage to extend the address space of a process. It provides an illusion of an extremely large main memory, even though the physical memory is much smaller. This is done by swapping pages of memory to and from secondary storage as needed.
Option A is incorrect because virtual memory is not an extremely large main memory. It is a technique that uses secondary storage to extend the address space of a process.
Option B is incorrect because virtual memory is not an extremely large secondary memory. It is a technique that uses secondary storage to extend the address space of a process.
Option D is incorrect because virtual memory is not a type of memory used in super computers. It is a technique that can be used on any computer.
