When I was doing the JAA IR exams in 2011 I found a really obvious correlation between which was the right answer and which answer was the longest (the most verbose). Specifically, this strategy would probably enable your grandma to pass:
1) Eliminate any options which are obviously nonsense (admittedly this needs a bit of knowledge of aviation)
2) If it is a question of a regulatory nature, go for the one which is second-strictest
3) If it is a question on a compromised terrain clearance (e.g. flying in cold / low pressure air) go for the lowest actual altitude
4) Go for the one with the longest answer
One can easily see the aspect of human psychology (and laziness) which led to the above.
I have just been told by another pilot from eastern Europe that his country had a full list of PPL questions published openly by the CAA, in which, conveniently, the first answer was always the correct one 
5) Eliminate pairs of equivalent answers (some knowledge of aviation would help, too), e.g.:
Shifting CG rearwards would:
a) Increase stability
b) Decrease stability
c) Decrease controllability
d) Have no effect on stability or controllability
You are assuming that there is only one correct answer. Often, there is more than one The UK CAA appears to have removed most of those cases from their own version of the JAA QB, though the online QBs have not had the benefit of that “quality control” and they are still full of crap.
BTW I would have thought that b) and c) above would be equivalent
And a) is the right answer.
Moving the CG aft reduces the lever arm and also unloads the tail plane thereby reducing stability…
btw. Fighter jets have trade low stability for high maneuverability (controllability)… ie they are opposite effects.
I would never equate maneuverability with controllability, so there is yet another trick question which would cause somebody who has a reasonable knowledge of how a plane flies, into giving a wrong answer
Good point
This was actually a real question in the ATPL exam. The concept of ‘controllability’ as discussed in the textbook had more to do with control authority than maneuverability (with a CG forward of limits you may not have enough elevator authority to land properly).
And that just about sums up how silly the theory is. It is so theoretical that it makes quantum physicists seem like pragmatic engineers in comparison.
The question is not overly theoretical, it’s just very poorly worded. Clearly, a rearward CofG would make the aircraft both very unstable and very difficult to control. Controllability is not even a straightforwardly defined aerodynamic term so has no place in the question in the first place.
But commercial pilots should understand the theory behind this stuff.
“The question is not overly theoretical, it’s just very poorly worded. Clearly, a rearward CofG would make the aircraft both very unstable and very difficult to control….”
Yes, but it does make you go faster! 
