MS-DOS basics: After booting a DOS-based system, which command reports the operating system version currently running?

Introduction / Context:
Identifying the precise operating system version is a first step in DOS troubleshooting and software compatibility checks. MS-DOS provides simple, built-in commands to reveal this information without third-party tools.

Given Data / Assumptions:

• The user is at a DOS prompt after boot.
• They need the OS version, not disk layout or directory contents.
• Standard DOS internal commands are available.

Concept / Approach:
The DOS internal command VER (short for “version”) displays the current DOS version string. Other common commands serve unrelated purposes: DIR lists files, FORMAT prepares a disk, and DISK is not a standard DOS internal command for reporting OS version.

Step-by-Step Solution:

Verification / Alternative check:
In some DOS derivatives or Windows command prompts, ver similarly returns the version of the environment. This cross-check reinforces the correctness of using VER.

Why Other Options Are Wrong:
FORMAT alters disks and does not report OS version. DIR lists directory contents only. DISK is not the correct command for this task. “None of the above” is invalid because VER is correct.

Common Pitfalls:
Running commands that change media (FORMAT) when you only need information; confusing DOS with Windows version reporting tools.

Final Answer:
VER