A punctuation question with extra information tests whether you can find both ends of a detail. Read past the blank for a possible closing mark and find where the main sentence picks up again. Then cross out the extra information to check that the sentence still works without it. An insert is a detail you can remove; in the middle of a sentence, it needs matching marks at both ends. Marks nearby may have other jobs, so track the whole detail.
Hints
- Hint 1
Find where the sentence tells you what the researchers did. What are the words before that part doing?
- Hint 2
Try crossing out the words about how long filming lasted. Does the rest still tell you when the researchers visited the islands?
- Hint 3
Check each punctuation mark in context. Does it fit the words before and after the blank and the punctuation already in the sentence?
Step-by-step
Cross out the detail and match its ends
Step 1Find the main sentence
During the filming of the begins a phrase telling us when something happened, not who did what. Even with documentary added, it's not a complete sentence on its own. Where does the main sentence begin? After the blank, researchers visited more than fifty remote islands gives us who did what, so we need to find why there's a break between the filming and that visit.
- Step 2
Test the extra detail
The words process that lasted nearly three years describe the filming rather than say what the researchers did. Can we cross out that description and still have a sentence? Without it, the sentence still says the researchers visited remote islands during the filming of the documentary. That makes the process phrase an insert, extra information the sentence can do without. The blank falls at the start of this insert, while the sentence picks up again with the researchers' visit.
- Step 3
Match the two ends
The punctuation in three years—researchers visited shows that a dash closes the insert. How must we open it? An insert in the middle of a sentence needs matching marks at both ends, so the blank needs the same kind of mark. The version documentary—a opens the detail with a dash to match the one already printed at its end. Choice B.