Before the Civil War, Harriet Tubman, along with other former slaves and white abolitionists, helped create what had become known as the Underground Railroad, and were responsible for leading hundreds, if not thousands, of slaves to freedom.
1.had become known as the Underground Railroad, and were
2.would become known as the Underground Railroad, and were
3.had become known as the Underground Railroad, and was
4.has been becoming known as the Underground Railroad, and was
5.would become known as the Underground Railroad, and was

its Clear C....

Before the Civil War, Harriet Tubman, along with other former slaves and white abolitionists, helped create what had become known as the Underground Railroad, and was responsible for leading hundreds, if not thousands, of slaves to freedom.

I would also go with E.

Harriet Tubman helped create what would become known as the Underground Railroad.

The OA is E.

The original sentence contains two flaws. First, "what had become known as the Underground Railroad" is incorrectly in the past perfect tense ("had become"). The past perfect is used to describe a past event that occurred before another past event. In this case, however, the "Underground Railroad" did not become known as such (or known as anything at all) until after it was created, and there is no past action that occurs afterward that would justify the use of the past perfect tense. Second, the subject of the sentence is "Harriet Tubman" only; phrases such as "along with," "accompanied by," and "as well as" do not create plural subjects (only "and" allows for the formation of a plural subject). Yet, the verb used in the original sentence is "were," which suggests a plural subject. Instead, the correct verb form "was" is necessary in order to agree with the singular subject "Harriet Tubman."

(A) This choice is incorrect as it repeats the original sentence.

(B) This choice corrects the verb tense by replacing the past perfect with the conditional "would become known" (used to express the future from the point of view of the past: "I said yesterday that I would go to the store today.") However, it does not correct the subject-verb agreement problem (retaining "were").

(C) This choice does not correct the verb tense issue, retaining the incorrect past perfect tense. It does correct the subject-verb agreement by replacing "were" with "was."

(D) This choice uses the incorrect and awkward verb phrase "has been becoming," which incorrectly suggests that the labeling of the Underground Railroad continues to the present day. However, it does correct the subject-verb agreement by replacing "were" with "was."

(E) CORRECT. This choice corrects the verb tense by replacing "had become" with "would become." Moreover, it corrects the subject-verb agreement issue by replacing "were" with "was."

+1 for E

Use "would" if the event is in past and talking about the outcome in the future.

D : sequence of events is wrong.

t1 : HT helped create
t2 : it later became known as Underground Railroad

t1 happened before t2 on time line. D says the other way round.

E fixes all of this.
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