Open vs Open source software

I had an online quizz last week and there was the following question:
_________ software is software that can be used, modified, improved, and redistributed.
Utility
Operating
Driver
Open
System
Application
None of the above

The right answer was open-source software, there is no debate about that, but I selected "none of the above" instead of "open" because I considered "open" to be only half of the actual answer. Turns out it the website considered it to be the right one. Yet the book always made mention of open source, and never simply "open".

I contacted the teacher but he says because there is no other meaning for open software, it is as valid as open source software. I disagree!

I've been telling him that other than the online exam, I've never seen any website mentioning "open software" instead of "open source software", that O.S.S. stands for Open Source Software, not open software... we'd say O.S. otherwise, right?... but no that's operating system! Also, that open doesn't specify that the SOURCE is what is open, which makes it possible to modify, improve, etc.

Who's right, who's wrong?

You are arguing semantics. See Bill Clinton in his argument of what the definition of "is" is. As someone who has had the misfortune of grading before, I almost never accept semantics as a justification, because it shows a logic process that identifies the most probable correct answer, but nevertheless, selects an less probable answer instead, because the person is a total wanker.

In multiple choice you choose the best answer, which makes open the correct answer in this context. Whether or not the question is poorly thought out doesn't take away from this point. That said a quick google shows the phrase open software being used to refer to open source software. If you really want to be anal open source might also refer to source-available where the source is available but the right to modify and/or distribute isn't.

Originally Posted by AlmostFullBenefits

Click to expand...

You are arguing semantics..
The question is about semantics, which would make arguing about semantics appropriate. It is asking you to attach a word out of a list to a definition after all.