A punctuation question tests how words on either side of a blank fit together. First, read both sides of the blank, setting aside details between paired dashes. Then check which parts can stand alone, with a subject, a main verb, and a complete thought. A colon introduces a list or explanation after a full sentence; a semicolon joins two full sentences. A comma with and joins full sentences, while and can also join matching words or phrases. Because introduces a reason with a subject and main verb.
Hints
- Hint 1
Look at the words before the blank. Does the first part make a complete statement once its final name is given?
- Hint 2
Read past the detail between the paired dashes. Does frozen work as a main verb on its own, or would it need a helper?
- Hint 3
How do the words about inclusions connect to what the geologists call diamonds?
Step-by-step
Test the sentence, then the description
Step 1Test the words before the mark
Complete Geologists sometimes refer to diamonds as with the name given by every choice. Since we're choosing punctuation, can this first part stand alone? It can, because the geologists are the subject and refer is the main verb, with the name finishing the thought. The completed first part is a full sentence.
- Step 2
Read through the dashes
Now set aside the detail between the paired dashes and ask: does the rest have a main verb? The words name tiny inclusions, then describe them as frozen inside the crystals. That description would need a helper verb, as in are frozen, to give the inclusions a main verb. The words after the blank are a phrase, not a full sentence.
- Step 3
Test the other links
What happens with the other ways to join the parts? A semicolon needs a full sentence after it, but these words can't stand alone. The version with because needs a subject and main verb to state a reason. A comma with and can join two full sentences, but here it joins a full sentence to a phrase. None of these links fits the parts on either side.
- Step 4
Attach the description
Why does the description follow the name? The minuscule inclusions are frozen inside the crystals, which gives a picture of things preserved within diamonds and explains the name time capsules. A colon links the full sentence to the phrase that explains it, so time capsules: completes the text. Choice B.