The correct answer is A. Swapping.
Swapping is a process of copying a process from memory to disk to allow space for other processes. This is done when the operating system needs to make room for a new process, but there is not enough memory available. The process that is swapped out is not lost, but it is not available until it is swapped back in.
Deadlock is a situation in which two or more processes are waiting for each other to release a resource that they need. This can cause a system to become unresponsive or even crash.
Demand paging is a technique used to manage memory in a computer system. It involves only loading pages of memory that are actually being used by a process. This can help to improve the performance of a system by reducing the amount of memory that is wasted on unused pages.
Page fault is an event that occurs when a process tries to access a page of memory that is not currently in memory. The operating system will then need to load the page from disk into memory before the process can continue.
