Thanks for the question! The correct answer choice here is (B). I'll walk through it so you can compare your diagram to mine. We have 6 objects that we need to put in order: rstvwz.
We know that S is 3rd or fourth. We know that WZ (W is directly in front of Z). Finally, we know that ~RV & ~VR (V and R aren't adjacent).
We're given a hypothetical and asked for an answer choice that must be true govern this hypothetical. So let's start off by putting the rope bridge in the second slot.
_ R _ _ _ _
Now, let's take a look at the first slot. We know that V can't go there, since V can't be adjacent to R. We know that S can't go there, since S has to be in slot 3 or 4. But we also know that W and Z can't go there because W and Z have to be adjacent, so they can only go in places where there's at least two slots next to each other. Well, if 4 of the letters can't go there and we've used another one, that leaves one letter left that can go there. Thus, we know that the tunnel is the first obstacle, and (B) must be true. Hope this helps!
