Known to its considerable opposition as "Seward's Folly", the purchase

When you first examine this question, there are several clear Decision Points: “not unlike” vs. “like” vs. “as” and “which provided” vs. “for providing.” The easiest Decision Point, however, is a little harder to notice: the choice between having “that of” and not having it. To make this a logical, apples-to-apples comparison you must have “that of” are you comparing the purchase of Alaska to “Louisiana” or “that of (meaning the purchase of) Louisiana”? “That of Louisiana” is necessary to make it a logical, purchase-to purchase comparison, so answer choices B and C are incorrect. Also, answer choice E is incorrect, because you do not use “as” to make noun-to-noun comparisons (but you will be able to eliminate it for other reasons as well). Importantly, the choice between “like” and “not unlike” is a classic false Decision Point; they could both be used here, but people often eliminate “not unlike” prematurely.

The remaining decision is more difficult and quite subtle, but you should at least know to assess it because of the obvious Decision Point. As you have seen in earlier examples, you will often want to scan the answer choices at the first and last words/phrases for differences, and here there is a 2-1 split between “territory, which provided” and “territory for providing” What is the difference? “Which provided” makes it clear that the Louisiana territory provided the new land, strategic position, and Mississippi River valley. “For providing” leaves that ambiguous at best, or assigns it to Alaska at worst. Either way, the meaning is either unclear or incorrect, and answer choices D and E suffer from this modifier reference problem.

Answer choice A—the choice that many eliminate upon first glance for the double-negative—is correct.