Sorry to say I do not even get the idea behind the test. The selected shapes make no sense to me in relation to music. I could probably figure it out by just guessing myself through the test first, but don't see the point...
Like many questions on IQ tests, these are associations. So for example, here is a non-musical association to shapes - that is, instead of shapes, I am using numbers - and I've exactly seen this (or something very close to it) before on IQ-like tests:
Is the numeric sequence "2 5 8 5 2" like the shapes /\ or the shape \/ or the shape <> or the shape  ? In this case, you one would consider the 5 numbers and note that they go up steadily to 8 and come back down the same way, so among the 4 visual shapes, the one that has the closest association would be the shape that also goes up and back down: /\.
This is how associations work between two types of objects which might not be immediately related. Obviously, in the case of the test, we are talking musical tones and not numbers, but frankly, tones and numbers map to each other.
I think now you might see how sequences of tones might relate to shapes. For example, if you have heard C-D-E-F-G-C-D-E-F-G, and you have a number of shapes to choose from, but one of them is / /, you might choose that one because it shows to identical lines slanting upward like the 'C-D-E-F-G'. On the other hand, you might not be given '/ /' as a choice, but instead one of the choices might be ' ' Well this might also be a good association. Why? Because 'C-D-E-F-G' repeats twice, just like the '' repeats a second time in the shape. Obviously here, you are simply trying to choose one set of shapes which is better
than the other choices. One final example: you hear C-D-E-F-G-C-D-E-F-G, but the second 'C-D-E-F-G' gets softer (diminuendo) while the first one stays at the same dynamic. One shape choice is ' ' and another is ' |>'. Here, the second one suggests the diminuendo while the first suggests an exact repeat, so you might select the second one instead as a better association than the first.
Do you understand how it works now, outo? If you've never seen this sort of thing before, I can completely understand your confusion.