Bunuel
The damage caused by the series of storms
were relatively minimal, but among the casualties were a cluster of farmhouses on the western outskirts of town.
A. were relatively minimal, but among the casualties were a cluster of farmhouses
B. were relatively minimal, but among the casualties was a cluster of farmhouses
C. was relatively minimal, but a cluster of farmhouses were among the casualties
D. was relatively minimal, but among the casualties was a cluster of farmhouses
E. was relatively minimal, but among the casualties were a cluster of farmhouses
VERITAS PREP OFFICIAL EXPLANATION:
As you scan this problem for decision points, you should recognize that you're dealing with subject-verb agreement: the first word of each answer choice is either "were" or "was," and a similar "were/was" decision occurs around the middle of each choice. With that, you should attack the problem looking for the subjects of each verb.
In classic GMAT style, the testmaker includes a series of nouns in the introductory phrase "the damage caused by a series of storms..." Here you should recognize that "of storms" is a prepositional phrase that modifies "series" and that "caused by a series" is a participial modifier describing "damage." Eliminating those modifiers should lead you to "damage" as the subject of that verb, meaning that you need the singular "was" from choices C, D, or E.
For the next "were" (C and E) vs. "was" (D) decision, you can again eliminate modifiers to better assess the subject. In "a cluster of farmhouses" "of farmhouses" is a prepositional phrase that tells you more about the cluster. So the true subject is "cluster," which is singular. As you need a singular verb "was," only choice D can be correct.
To make that decision more difficult, the testmaker uses and even more nuanced device to obscure the subject: subject-verb inversion. Instead of saying "a cluster of farmhouses was among the casualties" choices D and E put the verb ahead of the subject "among the casualties was a cluster..." This is a perfectly valid sentence structure (you see/use it more than you think:
-"Here is your money."
-"There is something about Mary."
-"Along came a spider."
The testmakers know that students are accustomed to scanning immediately before the verb to find the subject, so they frequently employ those two devices from this problem - including multiple nouns as part of modifiers, and subject-verb inversion - to make your job harder. Be comfortable with these structures and subject-verb agreement is a much easier decision point to attack.