What is operating system​

It's simply a software that runs a computer's basic tasks, or functions, such as scheduling, running applications, and controlling peripherals.

Operating System Definition: It is a software that works as an interface between a user and the computer hardware. The primary objective of an operating system is to make computer system convenient to use and to utilize computer hardware in an efficient manner. The operating system performs the basic tasks such as receiving input from the keyboard, processing instructions and sending output to the screen.Examples of operating system are UNIX, MS-DOS, MS-Windows – 98/XP/Vista, Windows-NT/2000, OS/2 and Mac OS.

answer(d) sequencing and iteration;