I understand that the part to focus on in this sentence is "the purchase of Alaska was not unlike that of the Louisiana territory, which provided ..."

I also understand why options D & E are incorrect. But I'm not clear as to why B & C are incorrect and as the book/on demand explains sets up an incorrect comparison to the Louisiana Territory. I thought this is exactly what we're comparing the purchase of Alaska to. Please further explain why B & C are incorrect.

The correct answer, choice A, makes it clear that it is the purchase of the Louisiana territory to which the purchase of Alaska is being compared.

Choices B and C illogically compare the purchase of Alaska with the Louisiana territory.

- Veritas Help

But how so?? What specifically regarding the wording is incorrect?

the incorrect answers in choice B and choice C lack the works "that of" to clarify that it is the purchase that is being compared.

-Veritas Help