A punctuation question with a long insert, or stretch of extra information, tests whether you can find where it starts and ends. Read around the blank to find both ends of the insert, looking past any marks inside it. Cross out the extra information to check that the remaining words form a complete sentence. An insert in the middle needs matching commas, dashes, or parentheses at its ends. Punctuation follows how the words work together, not where you pause.
Hints
- Hint 1
Start at “The spacing of those markings” and find the mark that opens extra information.
- Hint 2
Look for the verb that goes with the spacing. The words beginning with which have verbs of their own, so ask what each verb goes with.
- Hint 3
Cross out the whole insert, including the words beginning with which. Does what’s left tell both what the spacing does and what it acts on?
Step-by-step
Find and close the insert
Step 1Find the outer insert
The dash in markings—rather than comes right after the sentence names the spacing of the markings. What does it introduce? The words about the disks’ dimensions give a contrast, so the dash opens an insert, a stretch of extra information. The comma in dimensions, which introduces more detail about the dimensions inside that same contrast.
- Step 2
Find the spacing’s main verb
Which verb tells what The spacing of those markings does? In which first suggested that the objects served, suggested goes with the dimensions and served goes with the objects, so neither tells what the spacing does. The spacing’s main verb is supports, so the insert ends at function, before that verb. Cross out the whole contrast, including the words about what the dimensions suggested, and we get a complete sentence: the spacing supports the researchers’ proposal.
- Step 3
Match the mark and connect the verb
An insert in the middle must close with the same mark that opened it, so a dash belongs after function. What comes after supports? Its object, the thing it supports, is the researchers’ newer proposal, so no comma belongs between supports and the proposal. The version function—supports the researchers’ supplies the closing dash without adding a comma after the verb. Choice C.