A punctuation question with a long completion tests how sentences join and end. Split where the added words begin. A full sentence names who or what it's about, says what they do or are, and doesn't depend on more words. Two full sentences can take a period, a semicolon without a joining word, or a comma plus a joining word. Then check both ends of the completion, because its final mark must work with the next sentence too.
Hints
- Hint 1
Look at the sentence beginning with Scientists. Can it stand alone once the list of what whales use sound to do is complete?
- Hint 2
Find the subject and main verb in the added words. A different word order doesn't automatically make those words an incomplete sentence.
- Hint 3
Check the punctuation at both ends of the completion. How will the next paragraph's sentence connect to the words you've added?
Step-by-step
Check both sentence boundaries
Step 1Test the first sentence
Scientists continue to study gives us a subject, Scientists, which names who the sentence is about. The main verb, which tells what they do, is continue. Finishing the list with food makes this part a full sentence, so we need to test whether the added words can stand alone too.
- Step 2
Test the added words
Can the words about acoustic tags stand alone? Their subject is acoustic tags, and their main verb is have revealed, even though only recently comes first. So the added words also form a full sentence. The following paragraph begins Their vocalizations provide clues, which means we must check the completion's ending as well as its first join.
- Step 3
Apply the rule and check the question
Which version conforms to the conventions of Standard English? A comma plus but joins the full sentences. The joining word but connects the clauses, so a comma is the standard mark before it here. The commas in find mates, navigate, and locate separate items in a list; they don't call for a semicolon at this boundary. We also need a period after songs because the next paragraph starts a new sentence. Choice D.