Length contraction of a physical object In a peer-reviewed publication, one of the length-contraction effects of a physical object, depicted in the diagram, is used to derive conclusions. It has been referenced by other authors and in Wikipedia. The paper is not identified here intentionally, hopefully, to avoid bias in possible explanations.
Edit summary: The original diagram is modified in response to initial comments, to clarify that what was referred to as 'changes in the y-direction' is not relevant to the main question. Please ignore the ‘old set of drawings’ and kindly consider the same question with reference to the ‘new set of drawings”, as edited.

Question: Which of the bottom two diagrams in the edited drawing above shows (descriptively) the effect of length contraction for an object depicted with solid lines in the top diagram?
The old diagram is included below, for reference with the initial comments.

 A: EDIT:
The question has been altered with a new set of diagrams. There are no lengths given in the new (or old diagrams) nor are either the length contraction factor or the velocity given. So the question is slightly ambiguous. However, working with what we have we can say that

*

*The diagram which shows the thickness of the object reduced to about half, but the angle unchanged, is definitely wrong. If the thickness were reduced to about one half, the total extension in the X-axis would be reduced by about one half as well. One would see a very substantial change in the "angle" of the object.


*The diagram which shows the angle changed is wrong as well, at least if it is interpreted to show the thickness unchanged, as it seems to. Since the overall X-axis contraction is a smallish fraction of the overall X-axis extension, the change in the thickness of the object will be smallish, and might not be noticeable in the diagram. However, there are two clues that suggest that the thickness was not meant to change. One is the label "length contraction" which seems to suggest the only contraction occurred in the front. The second is the base of the object, which appears unchanged by the contraction. If the thickness of the object is not meant to change in this diagram, then it is wrong as well.


*A correct diagram would show both the overall extension (in the X-axis) changed, and consequently the "angle" of the object, and also the thickness of the object. Furthermore, both of those changes would be in the same proportion. If the overall extension (in the X-axis) changed by, say, 10%, the thickness would change by 10% as well.
ORIGINAL ANSWER:

Which of the bottom two diagrams shows (descriptively) the effect of length contraction for an object depicted with solid lines in the top diagram?

Neither.
The dimension in the direction of motion is contracted (the "x" dimension in this case). The other dimensions stay the same, (i.e. the y dimension). Both of the diagrams show a stretching in the y direction, which will not occur.
A: The effect of length contraction will be to make the object appear narrower in the x direction (ie more slender) and to reduce the apparent angle of tilt away from the y axis. None of the drawings you have supplied seems to depict that, although if you were to combine the reduced tilt from the left hand drawing with the more slender effect in the right hand drawing, you would capture the overall effect.
If you find it hard to convince yourself, imagine that you replace the object with a large square. You will find it easy to convince yourself that the effect of length contraction on the square will be to make it contract in the x direction so that it becomes a rectangle, taller than it is wide. For extreme length contraction the square will reduce to a tall and narrow rectangle. Now imagine that your slanting object was in fact just a shape painted on the square. You should now find it easy to appreciate that as the square condenses in one direction to become a tall narrow rectangle, the painted section will become both more upright and more slender.
A: Both are incorrect. That is, if the "top length" in the left picture equals that of the top picture. Both the angle with the y-axis as "top length" change.
