Operating Systems Basics Which of the following are major operating systems commonly used on computers (historical and contemporary examples)?

Introduction / Context:
Operating systems are the fundamental software layer that manages hardware resources and provides common services for applications. Familiarity with representative operating systems helps learners connect historical platforms to modern descendants such as Windows, Linux, and macOS.

Given Data / Assumptions:

• The examples listed (MS-DOS, OS/2, UNIX) refer to families of operating systems used on personal computers and workstations.
• “Major” means widely used or historically influential in computing development.
• We evaluate whether each candidate qualifies as a major OS family.

Concept / Approach:
Determine the historical impact, user base, and technological influence of each system. If each item meets the criteria, then the most inclusive option is correct.

Step-by-Step Solution:
MS-DOS: Dominated early IBM-PC compatibles; provided the basis for early Windows versions.OS/2: IBM/Microsoft project later driven by IBM; important in enterprise desktops and ATM/industrial systems.UNIX: A seminal multiuser, multitasking OS; foundation for many variants (AIX, Solaris, HP-UX) and UNIX-like systems (Linux, BSD, macOS).Since each item is a notable OS lineage, the comprehensive choice is “All of the above”.

Verification / Alternative check:
Look at software ecosystems and standards: POSIX traces to UNIX; the PC software boom started on MS-DOS; OS/2 influenced later Windows NT concepts and lived long in niche domains.

Why Other Options Are Wrong:
Individual selections (MS-DOS, OS/2, UNIX alone) omit other valid examples.“None of the above” is incorrect because all three are legitimate OS families.

Common Pitfalls:

• Thinking “major” must mean “current market share only.” Historical importance also matters.
• Confusing UNIX with Linux; Linux is UNIX-like but influenced heavily by UNIX.

Final Answer:
All of the above.