Operating System (OS)
Memory management is :

replaced with virtual memory on current systems
not used on multiprogramming systems
not used in modern operating system
critical for even the simplest operating systems
None of these

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Operating System (OS)
The term "operating system" means

the way a computer operator works
conversion of high level language into machine code
the way a floppy disk drive operates
None of these
a set of programs which controls computer working

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