Final Answer:
Swapping must be done when a process has pending I/O, or has to execute I/O operations only into operating system buffers thus option A is correct.
Step-by-step explanation:
In computer science and operating systems, swapping must be done when a process has pending I/O or has to execute I/O operations only into operating system buffers. Swapping is a technique used in operating systems to manage memory efficiently. When a process has pending Input/Output (I/O) operations or needs to execute I/O operations directly into the operating system buffers, it is essential to perform swapping.
The "must" in this context emphasizes the necessity of swapping in certain situations, specifically when dealing with processes that involve I/O operations. Swapping involves moving parts of a process in and out of main memory, allowing the operating system to efficiently manage memory resources. This ensures that processes with pending I/O operations can proceed smoothly without being hindered by memory constraints.
Therefore, the correct answer is "a) Must," indicating that swapping is a mandatory operation in scenarios involving pending I/O or processes requiring direct I/O operations into operating system buffers. This adherence to swapping protocols contributes to the effective functioning of the operating system and overall system performance.