As bank staff streamed into work the next morning

OFFICIAL EXPLANATION

THE PROMPT


THE OPTIONS

• Subject/verb agreement
→ The singular subject presence does not agree with the plural verb were.

• who / that
→ The phrase should be "officials who wore."
→ to describe human beings, use who.
To describe anything non-human, use that.

GMAC is quite strict about this distinction.
Correct: The student who displayed graciousness left a memorable impression.
Correct: The cluster bombs that invaders use on civilian targets are barbaric.

Occasionally you will see a group constituted of people—such as a battalion, a government, or a committee—followed by that.
Such usage is allowed. You will not see a question in such a case in which who is pitted against that.
Example, allowed: The Ukrainian regiments that held off the Russian invaders were outgunned and outmanned but fought more cleverly and more tenaciously.
Eliminate A


• I do not see any errors

• The singular subject presence agrees with the singular verb was

• Who/that is not an issue, although the perfectly acceptable modifier "wearing" comes from a "reduced relative clause."
Original relative clause: . . . SEC officials who were wearing their . . .
To reduce this clause, remove the relative pronoun (who); remove the to be verb (were); and leave wearing.

• Characteristic is an adjective that describes a noun.
You will often see it paired with a possessive term such as their, her, etc.
Wearing black suits is characteristic of SEC officials.
The black suits are not characteristically doing anything.

Characteristically is an adverb that describes a verb; frequently that verb is a linking verb.
Correct: Conspiracy theorists are characteristically bitter and often espouse nihilistic ideologies.
Correct: Journalists characteristically open their stories with 25 to 30 words and often do so in one sentence; that sentence is called a "lead."

I recall only a couple of official questions in which this split has shown up, and I believe that the split was not decisive. (The answer choices were eliminated on the basis of other errors.)

Still, you never know what you will see, so if you can, just notice that the adverb characteristically has the common suffix -ly whereas the adjective characteristic does not.
And choose the safe route.
The adverb modifies a verb. The adjective modifies a noun.

I advise against doing a Google search for "characteristically black."
Getting hits on Google is not typically great support for what is considered correct on the GMAT.
In similar fashion, do not take the word of a dictionary or its collocation notes as gospel.
KEEP


• who / that
→ The phrase should be "officials who wore."
→ to describe human beings, use who.
To describe anything non-human, use that.
Same error as that in option A.

• characteristically is an adverb that should modify a verb, but in its placement in this sentence, characteristically incorrectly modifies the noun black suits
ELIMINATE C


• Nonsensical
The word "of" renders the whole sentence nonsensical.
Incorrect and nonsensical: The presence of SEC officials . . . was an ominous sign of the staff's employer in trouble.
ELIMINATE D


• Nonsensical: OF.
Same error as that in option D.

• Characteristically should be characteristic
Same error as that in option C.
Eliminate E

The answer is B.

COMMENTS

I like the discussion on this thread.
And for the most part, these answers are excellent.

Keep up the good work.