Although they were initially very popular in much of Europe and Mexico

IMO D

A. they were initially very popular in much of Europe and Mexico, after John Gerard wrote The Generall Historie of Plantes in 1597, the English and its colonists expressed concern that tomatoes are -> they refers to the English and its colonists.. hence wrong

B. tomatoes were initially very popular in much of Europe and Mexico, after John Gerard wrote The Generall Historie of Plantes in 1597, the English and its colonists expressed concern that -> that??

C. tomatoes were initially very popular in much of Europe and Mexico, after John Gerard wrote The Generall Historie of Plantes in 1597, the English and their colonists expressed concern about them being -> them being is wrong

D. tomatoes were initially very popular in much of Europe and Mexico, after John Gerard wrote The Generall Historie of Plantes in 1597, the English and their colonists expressed concern that tomatoes are -> Correct.. though it should its colonists

E. they were initially very popular in much of Europe and Mexico, after John Gerard wrote The Generall Historie of Plantes in 1597, the English and their colonists expressed concern that tomatoes are -> same as A

Official Explanation:

Read the original sentence carefully, looking for errors:

The underlined part of the sentence begins with the pronoun "they," so that word needs to refer clearly to only one noun in the sentence. Note also that the parts of the sentence that are set off by commas ("Although..." and "after...") are modifying the main clause, so the first noun after the modifying clauses should be the noun that "they" refers to. Logically, the tomatoes were "initially very popular" before Gerard wrote his book, but the words that start the main clause are "the English and its colonies." Based on this error, you can eliminate (A).

But there is another issue in the given sentence. In the phrase "the English and its colonies," "the English" is short for "the English people." "People" is a plural noun, so there is a mismatch between a plural entity ("the English") and a singular pronoun ("its"). Eliminate (A) for this error as well.

Scan and group the answer choices:

Like the original, (E) begins with "they." (B), (C), and (D) begin with "tomatoes."

Eliminate choices until only one remains

(E) commits the same pronoun error as (A), with "they" referring to the English instead of to the tomatoes. Eliminate.

Among the remaining choices, (B) uses "the English and its," while both (C) and (D) use "the English and their." Since "its" is incorrect in this context, eliminate (B).

(C) and (D) are the same until the end, where (C) uses the weak "about them being." (D) uses the unambiguous noun "tomatoes" and active voice, with "that tomatoes are," and is correct.

TAKEAWAY: If a pronoun is underlined, check that it refers unambiguously to a noun and that it agrees with its antecedent (e.g., a plural pronoun replaces a plural, not singular, noun).