A punctuation question about extra information tests how you set off a description inside a sentence. Look around the blank to find both ends of the insert. Cross out the description, then check that what's left has a subject and its own verb. In the middle of a sentence, commas, dashes, or parentheses must match at the two ends. A verb inside the description can mislead you about where the main sentence picks up again.
Hints
- Hint 1
Look back from which for the mark that opens the description.
- Hint 2
Cross out the words about why the river flows backward and check where the sentence resumes. Then use the opening mark to decide how to close the description.
Step-by-step
Find and close the insert
Step 1Find the opening mark
The comma in The Chicago River, which opens a description of the river. What does that description add? It tells us why the river flows backward. It's an insert, extra information inside the sentence, so we need to find its end to punctuate the blank.
- Step 2
Cross out the description
The verb in which flows backward belongs to which, inside the description. Where does the main sentence pick up again? It picks up at is, the river’s own verb. Every choice puts is before now a popular kayaking route. Cross out the description through project: The Chicago River is now a popular kayaking route. The sentence works without the insert, which ends before is.
- Step 3
Match the closing mark
How do we close the description opened by the comma in The Chicago River,? The closing mark must match the opening mark, so we need a comma after project and before is. The choice project, is adds that closing comma and lets the main sentence continue. Choice D.