>> I just ask about what the person consider the most effective structure for a table to hold this hierarchy.
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>The correct answer to any question is the one the person asking the question is willing to accept. If a question is communicated clearly it should be answered in a similar manner. If a question is not clear it should be qualified.

Hello, Tom.

I agree with you. Of course I'm not expecting a specific answer. And I didn't presented the question as clean as I can in the printed test I hand to the person that do the test.

What this question tries to judge is how the person work out the problem. Some people had gave different and correct alternatives, and some even gave wrong ones but with a clear understanting a correct logic, just mistaken the final response. And I considered many of those ok.

The issue about this question (of course are many more simmilar at this), is that is just a usual, real life case that a seasoned programmer already knows about (and understand quite good), and a new one can perfectly reason using simple logic, if she/he is samrt enough.

Overall, I don't like multiple choice type questions. NOt for an interview, at least, I generally prefer make people explain why there are answering every thing, ro even draw little, hand written, diagrams.