Correct option is A
System calls provide an interface between a process and the operating system, allowing user-level processes to request services provided by the operating system. These services include tasks like file operations, process management, and communication, which are essential for running applications.
·
System calls: These are low-level functions provided by the operating system that enable user-level processes to interact with the hardware and other resources managed by the OS. They serve as the bridge between user-level applications and the kernel of the operating system.
·
API (Application Programming Interface): While an API provides a higher-level interface for developers to interact with software libraries and services, system calls are more fundamental and are often invoked indirectly via an API. The API might be a part of a library that wraps system calls for easier usage.
·
Library: A library is a collection of precompiled routines that a program can use. While libraries often contain APIs that interact with system calls, they are not the system calls themselves.
·
Assembly instructions: These are low-level instructions specific to a CPU architecture and are used in programming directly in assembly language. They are not directly responsible for interfacing with the operating system at the level of system calls.
Thus,
system calls are the correct answer as they provide the necessary interface between user processes and the operating system.
