Hello again,
After the initial two inferential set ups where do you go?
If r is third then s is second or fourth, because s has to be after p then we can infer p,s,r but that's it...
Secondly of we accept T and third then there are no other inferences without additional information.
Where am I going wrong? Thank uou

Christina,

Let's start by looking at the Stem Rule:

Here we've got:
[P, S]

Let's combine it with Rule 4, which states that we must have either [R, S] -or- [S, R].
We know we cannot have [R, S] if we have [P, S].
So we must have [S, R].

Let's combine [P, S] and [S, R]:
[P, S, R]

Now, by Rule 2 we know that we have:
U...[P, S, R]

What does this mean? It means that R CANNOT be 3rd (because we know that 3 other letters MUST come before R).
So, by Rule 3, T must be 3rd.

So if T is 3rd, then [P, S, R] MUST come after the 3rd slot.
This means that [P, S, R] must be in either [4, 5, 6] -or- [5, 6, 7].

Now let's look at our answer choices. We're looking for something that CANNOT be true.

(A) Can we have R, W? Seems possible. Let's move on for now.

(B) Can we have T, Q? Hmmm. Well, if we have T 3rd, then Q would be 4th.
That would mean [P, S, R] would be [5, 6, 7].
So for 3rd - 7th, we would have T, Q, P, S, R.
But Rule 1 says W MUST come after Q. And the scenario above leaves no room for that.
So choice (B) cannot be true, and it is the correct answer.

There is no need to test the other answer choices. (Though you can prove they are wrong if you'd like.)