OE:
Idiom; Rhetorical constructionThis sentence describes concern about a potential problem, which is
appropriately expressed in subjunctive mood (could be damaged). It
uses the idiom at a time when . . . to explain the current conditions that
make the possible future event a reason for concern. The pseudo-subject
there introduces unnecessary wordiness. In this sentence, a passive verb
emphasizes the speculative nature of the damage caused by the cold
snap in Brazil.
A. The phrase when at a time with is confusingly redundant and
incorrectly uses the idiom at a time when; the pseudo-subject there
introduces unnecessary wordiness.
B. The phrase at a time such as when is wordy and an incorrect idiom.
C.
Correct. This sentence correctly uses the subjunctive mood to
express a potential problem, and the idiom at a time when is correct.
D. The preposition of after concern is an incorrect construction, as is at
a time with.
E. The agency behind damaging is ambiguous; the verb has no clear
subject. The phrase at a time that is an incorrect idiom. As in D, the
preposition of after concern is incorrect.
The correct answer is C.