Question 221·Medium·Boundaries
Invented in the early 1900s, the ____ produces eerie, wavering tones that have become synonymous with classic science-fiction soundtracks.
Which choice completes the text so that it conforms to the conventions of Standard English?
For punctuation and appositive questions, first strip the sentence down to its core subject and verb to see what must stay together (here, "the theremin produces"). Then identify any middle phrase as essential or nonessential; nonessential descriptions like definitions or extra facts should be set off with matching punctuation (commas with commas, or dashes with dashes). Quickly test each option by mentally removing the phrase plus its punctuation: if the remaining sentence is complete and the marks match on both sides, you’ve likely found the correct choice.
Hints
Find the main subject and verb
Cover up the descriptive phrase and focus on the main subject and verb. What are the two main words that need to connect directly in this sentence?
Decide if the inserted phrase is essential or extra
Ask yourself: Does the phrase about the theremin give extra detail, or is it required for the sentence to make sense? How would the sentence read without that phrase?
Think about matching punctuation
For an extra descriptive phrase in the middle of a sentence, the punctuation before and after it should match. Look for the choice that uses the same type of punctuation mark on both sides and still leaves a complete sentence when the phrase is removed.
Test by removing the phrase and its punctuation
For each answer choice, imagine deleting the descriptive phrase and the punctuation directly around it. Which option leaves a smooth, grammatically correct sentence?
Step-by-step Explanation
Identify the core sentence
First, ignore the descriptive phrase to see the main structure of the sentence.
With the phrase removed, the sentence should read: "Invented in the early 1900s, the theremin produces eerie, wavering tones..." Because the blank comes after "the," the correct choice must begin with "theremin" and include any needed punctuation to set off the nonessential phrase.
Recognize the phrase as nonessential (an appositive)
The words "an electronic instrument played without physical contact" rename or explain "the theremin." This is an appositive phrase that is nonessential (the sentence still makes sense without it).
Nonessential appositives must be set off by matching punctuation marks on both sides: either commas on both sides or dashes on both sides.
Check each option for matching punctuation and sentence flow
Test how each option affects the sentence:
- With a comma before the phrase, there must also be a comma after it if using commas.
- With a dash before the phrase, there must also be a dash after it if using dashes.
- Mixing a comma on one side and a dash on the other, or using only one dash, is incorrect for this kind of phrase.
After removing the descriptive phrase and its surrounding punctuation, "the theremin produces" should remain intact.
Select the choice with a correct, matching pair of commas
Only one option surrounds the appositive with a comma before and a comma after it, yielding: "Invented in the early 1900s, the theremin, an electronic instrument played without physical contact, produces eerie, wavering tones that have become synonymous with classic science-fiction soundtracks."
This keeps the main sentence intact and uses proper punctuation for a nonessential appositive phrase, so the correct answer is "theremin, an electronic instrument played without physical contact," (choice C).