The correct answer is D. CP/M.
CP/M (Control Program for Microprocessors) is a single-user, single-tasking operating system that was popular in the 1970s and 1980s. It was designed for use on microprocessor-based systems, such as the Altair 8800 and the IBM PC. CP/M was one of the first widely-used operating systems, and it helped to popularize the use of personal computers.
PC-DOS (Personal Computer Disk Operating System) is a single-user, single-tasking operating system that was developed by Microsoft for IBM’s personal computers. It is a close derivative of CP/M, and it was the first operating system to be used on the IBM PC. PC-DOS was later renamed MS-DOS, and it remains in use today as a legacy operating system.
UNIX is a multitasking, multiuser operating system that was developed at AT&T’s Bell Labs in the 1970s. It is one of the most popular operating systems in the world, and it is used on a wide variety of platforms, including servers, workstations, and supercomputers. UNIX is known for its stability, security, and portability.
E. None of the above is not a correct answer.