Pronoun issue:
(A) & (B) has pronounced nd at the end of the underline. Other three do not have a pronoun:
>>> since you have a parallel structure with "...and...", one way you can deduce the structure is to (temporarily) eliminate the other half of that parallel structure.
in other words, since "is more than 2000 years old and..." is not underlined, it doesn't contribute to the structure at all, so you can ignore it. (this is the same way in which you can, for instance, detect pronoun case more easily: for instance, "john and i went to the theater" --> "i went to the theater".)
so, this is all you have to look at:
the army ... took the artisans more than 36 years to complete.
this is sufficient on its own, without a pronoun at the end, in much the same way as this: this test is hard to finish (not "hard to finish it").
**you don't need to repeat "it", since the army is already the subject.
for instance:
I took my bag and went home.
same deal here - "I" is already the subject of both verbs, by default. there's no need to say "...and I went home", a construction that would actually detract from the compactness of the sentence.**
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Run on: you can not add two independent clause with just a connector. You need comma + a connector.
>>>>(D) introduces a new independent clause (including a subject and verb), which is inappropriate without a comma in front of the "and".
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Parallelisms: the two verb doesn't have to be in the same tense.
>>>>>Think about the meaning of the sentence. The author is giving us two "wow" facts about this army of terra-cotta soldiers:
1/ It ___________.
2/ It took 36 years to finish.
What is fact #1?
Note: If you're reading the original prompt as you should"”focusing on what it's supposed to say, NOT on grammar"”then, by the time you're debating this split, you should already know what #1 is.
**"Is" and "took" are verbs with the same subject, so "is xxxx" and "took yyyy" are perfectly parallel**
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