_________ is a memory management scheme that permits the physical address space of a process to be noncontiguous.

Explanation:

Paging

• Paging is a memory management scheme by which a computer stores and retrieves data from secondary storage for use in the main memory.
• In this scheme, the operating system retrieves data from secondary storage in same-size blocks called pages.
• Paging is an important part of virtual memory implementations in modern operating systems, using secondary storage to let programs exceed the size of available physical memory.

Segmentation

• Segmentation is a memory - management scheme that supports the user view of memory.
• A logical address space is a collection of segments. Each segment has a name and a length.
• The addresses specify both the segment name and the offset within the segment. The user, therefore, specifies each address.

Fragmentation 

• Fragmentation is done at routers which makes them complex to implement when routers take too much time to fragment packets.
• This may lead to a DOS attack on other packets.

Swapping

• The medium-term scheduler reduces the degree of multiprogramming. Some processes are removed from memory to reduce multiprogramming. Later, the process can be reintroduced into memory, and its execution can be continued where it left off. This scheme is called swapping.
• The long-term scheduler, or job scheduler, selects processes from a mass-storage device and loads them into memory for execution.
• The short-term scheduler, or CPU scheduler, selects from among the processes that are ready to execute and allocates the CPU to one of them.