Question 233·Medium·Boundaries
An experiment demonstrated that switching streetlights to LEDs reduced energy use, but the full environmental benefits are still being assessed. Prior to the switch, the city’s annual electricity consumption for streetlighting was 15 gigawatt-hours, roughly the same as that of a neighboring ______ the switch, consumption fell to 9 gigawatt-hours.
Which choice completes the text so that it conforms to the conventions of Standard English?
For sentence-boundary questions, first identify the independent clauses (complete thoughts) before and after the blank. Decide where one sentence should logically end and whether the next part could stand alone as a new sentence. Then, choose the option that correctly uses periods and commas to separate complete ideas—avoiding run-ons (comma splices) and fragments—and read the full sentence with your choice to confirm it sounds clear and grammatical.
Hints
Find the two main ideas
Identify where the sentence talks about electricity use before the switch and where it talks about what happened after the switch. Ask yourself: should these be part of one sentence or two separate sentences?
Test completeness of the second part
Read just "After the switch, consumption fell to 9 gigawatt-hours." Does this form a complete sentence on its own? If so, you probably need punctuation that clearly separates it from the earlier part.
Look closely at punctuation around "city"
Focus on what comes immediately after "neighboring" and "city". Does the punctuation there properly end the first idea, or does it create a run-on or awkward phrase?
Eliminate comma errors
Try each option in the sentence. Cross out any choice that results in a long, clumsy sentence, a comma splice (two full sentences joined only by a comma), or strange phrasing like breaking up "after the switch" with an extra comma.
Step-by-step Explanation
Understand the structure of the sentence
Read the whole sentence with the blank:
"Prior to the switch, the city’s annual electricity consumption for streetlighting was 15 gigawatt-hours, roughly the same as that of a neighboring ______ the switch, consumption fell to 9 gigawatt-hours."
Notice there are two time periods:
- what happened prior to the switch
- what happened after the switch ("the switch, consumption fell to 9 gigawatt-hours")
That second part ("After the switch, consumption fell to 9 gigawatt-hours") is a complete idea that can stand as its own sentence.
Decide where one sentence should end
The first part compares the city’s electricity use to that of a neighboring city:
"…roughly the same as that of a neighboring city…"
Once that comparison is complete, we shift to a new point: what happened after the switch. That new point should not be tacked onto the same sentence with just a comma; it needs a clear separation.
So, grammatically, the sentence should end right after the word "city", and a new sentence should begin with "After the switch, consumption fell to 9 gigawatt-hours."
Check which punctuation marks create correct boundaries
Now look at what each choice does right after "neighboring":
- Some choices keep everything in one long sentence or insert commas in odd places. Those tend to create comma splices (two independent clauses joined by only a comma) or awkward, ungrammatical phrases.
- We need punctuation that ends the first sentence after "city" and starts a new one with "After the switch, consumption fell to 9 gigawatt-hours."
Only the choice that places a period after "city" and then continues with "After the switch…" correctly separates the two independent statements.
Match this to the answer choices
We want the sentence to read:
"Prior to the switch, the city’s annual electricity consumption for streetlighting was 15 gigawatt-hours, roughly the same as that of a neighboring city. After the switch, consumption fell to 9 gigawatt-hours."
The only option that produces this correct punctuation and sentence boundary is C) city. After.