Question 53·Medium·Boundaries
Marine biologist Dr. Andrea Singh’s paper describes the coral reef as an “archival library,” a metaphor that, according to _____ illuminates the reef’s role in preserving ocean history.
Which choice completes the text so that it conforms to the conventions of Standard English?
For punctuation-boundary questions, first strip away any interrupting phrases to reveal the core sentence and check that it is complete. Then decide whether the inserted phrase is essential or nonessential: nonessential information should usually be surrounded by commas (or matching dashes/parentheses), while essential information should not be. Finally, test each option by reading the full sentence with that punctuation choice—reject answers that leave you with mismatched punctuation, break the grammatical structure, or misuse colons and dashes (which generally must follow a complete clause and introduce something).
Hints
Find the main sentence without the interruption
Try covering up or imagining the words "according to ____" are removed. Does the remaining sentence read smoothly and make sense on its own?
Notice the comma before "according to"
Look at the words right before "according to." There is already a comma there. What kind of phrase usually appears between two commas in the middle of a sentence?
Think about what colons and dashes do
Ask yourself: Are colons and dashes normally used inside the middle of a sentence like this, or do they usually come after a complete thought to introduce an explanation or list?
Step-by-step Explanation
Strip the sentence to its core
First, ignore the interrupting phrase and find the main structure.
If we temporarily remove the words "according to ____," the sentence becomes:
"Marine biologist Dr. Andrea Singh’s paper describes the coral reef as an "archival library," a metaphor that illuminates the reef’s role in preserving ocean history."
This version is a complete, grammatical sentence. That means "according to ____" is extra information inserted into the middle of a clause.
Recognize the interrupting (parenthetical) phrase
Now look at how that extra information is placed:
"... a metaphor that, according to ____ illuminates the reef’s role ..."
The words "according to [name]" interrupt the clause "a metaphor that illuminates the reef’s role ..." This is a nonessential (parenthetical) phrase, which is normally set off from the rest of the sentence with matching punctuation marks (most often commas). We already have a comma before "according to," so we need a punctuation mark after the name to close off this interruption.
Decide what kind of punctuation is appropriate
For a mid-sentence interruption like this, the normal, standard choice is commas around the phrase (", according to Singh,").
A colon or dash is usually used
- after a complete thought (an independent clause) to introduce an explanation, list, or emphasis, not inside the middle of a clause like this.
Also, colons and single dashes here would not match the comma already used before "according to," so they would create an inconsistent and ungrammatical boundary.
Match the reasoning to the answer choices
We have determined that:
- The phrase "according to Singh" is a nonessential interruption.
- It must be set off with commas on both sides, and we already have the first comma before "according."
- Therefore, the correct option must place a comma immediately after "Singh".
Only choice B) Singh, supplies that comma, so the correct answer is B) Singh,.