A punctuation question with a long description tests whether you can track extra information inside a sentence. Find who or what the sentence is about and what it says they do, then cross out the description to check that the sentence still works. Extra information, called an insert, needs matching marks at both ends in the middle of a sentence: commas, dashes, or parentheses. Marks inside the insert may set off smaller details, so check what each one opens or closes.
Hints
- Hint 1
Read the second sentence and find what the fragments do. Which words describe the fragments before the sentence reaches that point?
- Hint 2
Look at the words between the two commas. Do they include the whole description of the fragments, or only a detail inside it?
- Hint 3
Mentally remove the description between “The fragments” and “provide evidence.” Find the mark that opened that description and ask what its other end needs.
Step-by-step
Trace the insert and match its ends
Step 1Find the interrupted sentence
In The fragments—once classified, the dash starts a description of the fragments. Which words tell us what the fragments do? They provide evidence, so provide is their main verb. For this punctuation question, we need to test whether the description is an insert, extra information we can cross out before the main verb.
- Step 2
Separate the inner detail
Do the commas already end the description? They surround after multispectral imaging, which tells us how the diagrams were found. The words to bear diagrams of branching still describe what the fragments are now known to bear, so the larger description continues after the second comma. Those commas close only the imaging detail. The full insert covers both the earlier label of debris and the diagrams found beneath the crusts.
- Step 3
Test the full insert
Cross out the description from its opening dash to the blank. We get The fragments provide evidence that local planners recorded changes in the canal network, so the whole description is extra information. The version with a semicolon can't work because that mark joins complete sentences, and the words before the blank haven't reached the fragments' main verb.
- Step 4
Close the matching pair
Which mark can close this insert? The dash in The fragments—once classified opened it, so a matching dash must close it before provide evidence. The version with a comma mixes marks, while the version with no punctuation leaves the insert open. waterways— supplies the closing dash before the fragments' main verb. Choice D.