A punctuation question tests how clauses connect at a blank. Test each side as a sentence: it needs a subject and main verb, with no word making it depend on another clause. Check the opening word as you read. A period or semicolon separates complete sentences; a comma joins an opening dependent clause to a main clause; a dash sets off extra words or a sudden break. Read the whole clause, since a complete sentence inside it doesn't make the whole clause complete.
Hints
- Hint 1
Read the opening from Although through the blank. Find the subject and main verb of that whole opening, not only the words about the medication.
- Hint 2
Ask what Although makes you wait for when you read the opening on its own. Does the subject and verb finish the thought, or does the first word make it depend on what comes next?
- Hint 3
Now test whether the words about the large-scale studies can stand alone. Use that result to decide how those words connect to the opening.
Step-by-step
Compare the marks, then test the clauses
Step 1Find the parts the punctuation connects
The sentence begins Although a recent review concluded and then shifts to what large-scale studies report. The punctuation connects these two parts. Let's read the whole opening through the blank and the whole part after it, because the mark has to fit how those parts depend on each other.
- Step 2
Test the whole opening
Can the words before the blank stand alone? In a recent review concluded, review is the subject and concluded is the main verb, which tells what the review did. But Although means even though, so it makes the whole opening a dependent clause, a clause that can't stand alone. Even with safe supplied, we're waiting to hear what happened despite the review's finding.
- Step 3
Find the complete main clause
Who does what after the blank? The words large-scale studies report rare but serious cardiovascular side effects have studies as their subject and report as their main verb. No word makes this thought depend on another clause, so this is the main clause, the part that can stand alone.
- Step 4
Close the opening with a comma
An opening clause introduced by Although needs a comma before the main clause. The dash version makes a strong break where the dependent opening needs a comma. The version with a comma joins the review's finding to the studies' report in one complete sentence. Choice C.