Question 167·Medium·Boundaries
Archaeologists recently uncovered the ruins of an ancient port city buried beneath the sands of Egypt. The site’s central ______ ringed by bustling markets—consists of towering basalt walls that still bear inscriptions.
Which choice completes the text so that it conforms to the conventions of Standard English?
For boundary/punctuation questions, first identify the core independent clause (subject + main verb) by mentally removing interrupting descriptive phrases. Then decide whether the removed words are nonessential; if they are, they must be set off with matching punctuation on both sides (two commas, two dashes, or two parentheses). Finally, reread to ensure you haven’t introduced an extra main verb or used a semicolon without two complete sentences.
Hints
Strip the sentence down
Ignore the description about the markets for a moment. What are the subject and the main verb of the sentence without that extra description?
Decide if the market description is essential
Is the information about being ringed by markets required for the sentence to be complete, or is it extra detail inserted in the middle?
Match the punctuation that’s already there
There is already a dash after “markets.” What punctuation mark would need to appear before the interrupting description to match it correctly?
Step-by-step Explanation
Find the core sentence
Temporarily remove the interrupting description (the part about markets) and its punctuation. The sentence becomes:
- “The site’s central structure consists of towering basalt walls that still bear inscriptions.”
This is a complete, correct sentence with subject “structure” and main verb “consists,” so we should not add another main verb before “consists.”
Identify the interrupting phrase
The words “once ringed by bustling markets” describe “structure” but are not required to make the sentence grammatically complete. So they are nonessential (parenthetical) information inserted between the subject (“structure”) and the verb (“consists”).
Use matching punctuation
The text already shows a closing em dash after “markets”: “markets—consists …”
To correctly set off a nonessential interrupter with dashes, we need a matching opening dash before the interrupter begins.
Choose the option that creates a correct dashed interrupter
Filling the blank with “structure—once” gives:
- “The site’s central structure—once ringed by bustling markets—consists of towering basalt walls that still bear inscriptions.”
The interrupter is enclosed by matching dashes, and the core sentence remains grammatical. Therefore, the correct answer is structure—once.