First lets analyze the question type : Must be True .

So we must consider the information given in the stimulus as true and answer options as suspect .


Since this is a Must be True question type we do not have a conclusion.

Premise 1 : If weak manufacturing sectors resulted in high rates of unemployment, states with the weakest manufacturing sectors would also have the highest rates of unemployment.

Premise 2 : In reality, however, when manufacturing statistics are adjusted so that different states are reliably comparable to each other, there is no correlation between weak manufacturing sectors and high rates of unemployment.

Now lets look at answer options :

(A) The weaker a state's manufacturing sector, the more likely that state is to offer unemployment insurance.
[this statement directly contradicts with the information in premise 2 , eliminate]
(B) If a state's manufacturing sector becomes stronger, its unemployment rate will not necessarily fall.
[This looks like a good answer and a contender as it agrees with the information in stimulus. ]
(C) It is not possible to compare the manufacturing statistics of two states reliably.
[This is trap answer and exactly the kind of trick that GMAT plays with you . This statement uses words that are common with the stimulus "when manufacturing statistics are adjusted so that different states are reliably comparable to each other" We can see that two sates' manufacturing statistics can be compared after adjustment and this dose not mean that we can compare them reliably , eliminate]
(D) When states are ranked in terms of total economic output from largest to smallest, the smallest states generally have the strongest manufacturing sectors and the lowest rates of unemployment.
[this statement directly contradicts with the information in premise 2 , eliminate]
(E) States with the highest rates of unemployment never have especially weak manufacturing sectors.
[this statement directly contradicts with the information in premise 2 , eliminate]


So the only correct answer is B .