I'm no fan of Mensa, but there's one thing that I don't understand in this article - if the test was for non-English speakers and it contained pictures of animals, why was one of the possible answers that popped into the author's head "sheep - because it has five letters". That's language-specific, and should not be regarded as a valid answer in a language-neutral test. But the point is, it seems to me that the author is trying to find holes in the test. Of course that "hen" is not the only possible answer. As the author suggested, meat of pigs, for example, is not kosher. We can find things that differentiate any one of those animals from the rest. In any set, you can find some property of any object that will differentiate it from the rest. But that's not the point, is it? The point is to find the most obvious answer. The same goes for sequences of numbers. Yes, you can continue a sequence of numbers with any number that you like, and your answer will be perfectly valid. But the point is to find the most obvious one.