The original sentence is intended to give information about the purchase of land which resulted in the increase of territory and other benefits.
Choice A
In the Louisiana Purchase of 1803, the United States acquired 828,000 square miles for about four cents an acre,
which more than doubled the country's size and
that brought its western border within reach of the Pacific Ocean.
Which refers to
four cents an acre instead
which should refer to acquisition of square miles. Moreover
which and
that are not parallel
Choice B
B. For about four cents an acre the
United States acquired, in the Louisiana Purchase of 1803, 828,000 square miles, more than doubling the country's size and
it brought
The sentence's main subject is the
United States.
It refers to the square miles, the acquisition or the Unites States? Not clear. Moreover, the opening of the sentence is weak. The reason is that the appositive" in the Louisiana Purchase of 1803" is not a modifier but a preposition phrase. Remember that a modifier can be an adjective, adverb or a verb but not a preposition phrase. So it does not modify or add any value to the opening dependent clause- "For about four cents an acre the
United States acquired". Not a good choice for GMAT.
C. With the Louisiana Purchase in 1803, the United States acquired 828,000 square miles for about four cents an acre, more than doubling its size and bringing
It seems to be a good choice so far- Remove the opening phrase and read the sentence
the United States acquired 828,000 square miles for about four cents an acre, more than doubling its size and bringing ..... Looks good. A mistake that can be committed in this choice is if we consider "the United States acquired 828,000 square miles for about four cents an acre" as an appositive. The opening of the sentence does not contain a subject and verb, it is a phrase, therefore, we should not consider the sentence in inverted commas as an appositive.
D. The United States, in the Louisiana Purchase of 1803, for about four cents an acre, acquired 828,000 square miles, more than doubling the country's size, bringing
This choice is dubious at first glance. The reason is obvious
The United States- Subject Noun
in the Louisiana Purchase of 1803- Preposition Phrase
for about four cents an acre- Preposition phrase
acquired 828,000 square miles - contains a verb - acquired
As in choice B the subject noun should normally be modified after a comma and then a verb can come after the modifier. In this case there are two prepositional phrases between the subject and the verb. So this choice is incorrect
E. Acquiring 828,000 square miles in the Louisiana Purchase of 1803, the United States bought
it for about four cents an acre, more than doubling the country's size and bringing
Two errors- The usage of "it" is ambiguous. It creates redundancy & meaning error. When the land is already acquired you cannot buy it. I.E. in this case you either buy or you simply acquire .
The second reason is that the subject is not clear - Acquiring is a gerund- if a sentence starts with a gerund, the gerund is considered as the subject. However, United states should be the main subject and acquired should be the main verb. In this case the main verb is doubling(gerund). Therefore, this choice is incorrect.