A punctuation question with several changing marks tests both sentence endings and extra information. First, find the main sentence by following who does what, then cross out any side detail. A detail in the middle needs matching commas or dashes around it. Test both sides of the sentence ending: a semicolon joins full sentences, a colon follows a full sentence and introduces what explains it, and a comma alone can't join full sentences.
Hints
- Hint 1
Read from “The decoy may attract few” and follow what the decoy does. Where does the sentence about the decoy end?
- Hint 2
As you read through the blank, try crossing out any side detail. Does the main sentence still work without it?
- Hint 3
For the words beginning “its value to the seller,” check whether they stand alone and explain what came before.
Step-by-step
Find the main sentence, then test the marks
Step 1Follow what the decoy does
Read The decoy may attract few together with the words each choice adds, because we need to choose the punctuation around the added detail and at the sentence ending. Who can attract few buyers and still shape demand? Both parts tell what the decoy may do, so yet still shape demand continues the same sentence. The main sentence runs through demand, rather than stopping at anticipate.
- Step 2
Set apart the removable detail
What can we cross out without losing what the decoy does? The phrase an outcome the seller may anticipate comments on attracting few buyers and can be removed while the main sentence still works. It's an insert, extra information the sentence could do without, and matching marks must go around it in the middle of a sentence. The version with anticipate; can't close the comma after buyers, while the version with buyers an outcome never opens the insert at all.
- Step 3
Introduce the explanation
After demand, its value to the seller lies not in direct sales has its own subject and main verb, value and lies, so it starts a second full sentence. That sentence explains how the decoy shapes demand despite few buyers. A colon joins a full sentence to what explains it, but the version with dashes uses a comma after demand, making a comma splice, a comma alone between full sentences. The version with buyers, and anticipate, puts matching marks around the insert and uses demand: to introduce the explanation. Choice C.