The artwork of Vincent Van Gogh, mostly paintings executed in bright

The antecedent of the pronoun "they" is "artwork". But "they" is plural and "artwork"
singular, so we need to find a choice that changes "they" to "it". Moreover, "people
who a trip to a major city may be too expensive for" is incorrect. It should be "people
for whom..."
(A) This choice is incorrect as it repeats the original sentence.
(B) The pronoun "they" is incorrect, as is the construction "people who a trip to a
major city may be too expensive for."
(C) The construction "people who a trip to a major city may be too expensive for" is
incorrect.
(D) CORRECT. The pronoun "it" correctly refers to the singular antecedent "artwork"
and "for whom a trip to a major city may be too expensive" is the correct modifier of
people.
(E) The pronoun "it" is correct, but the construction "people who a trip to a major city
may be too expensive for" is not.