_ controls the way in which the computer system functions and provides a means by which users can interact with the computer.?

the oprating system is controls the way in which the computer system functions and provides a means by which users can interact with the computer.

The operating system from the above, though you could include the BIOS

A.    The operating system

(A) the operating system (ex. windows, dos, unix, etc.)

>>>>>>>>>>>>>>>>>>>>>>  A.    The operating system

Sir I just want to add that the os win10 has the continuum feature. This means u can log on to ur account and when u use a phone devise without any keyboard (only touch screen) it has screen that is most suited in a touch screen smart phone but the moment u attach a wireless or wired keyboard to the tablet the screen will change so that u can better utilize the keyboard. It may be added that u use the though screen  for short periods of time and for blogging and typing e mails on the net a keyboard is a better option that the touch screen.