A punctuation question tests where one sentence ends and another begins. Split where the choices change, then test each side on its own. Read past interruptions to find who or what does what, and check for words that keep a part from standing alone. Join two full sentences with a period, a semicolon, or a comma plus a joining word like and. Attach a part that can't stand alone with a comma or no mark.
Hints
- Hint 1
Find the subject and main verb before the blank. Read through the thought about the sash to decide whether it can stand alone.
- Hint 2
Look for what proved compelling, then read past any words between that subject and its verb.
- Hint 3
Read each whole part, including its opening words. Ask whether it can stand alone, not only whether it has a subject and verb.
Step-by-step
Split and test the sentences
Step 1Test the first thought
Microscopic analysis challenged the curator's assumption has a subject, analysis, and a main verb, challenged, which says what it did. Complete the thought with the shared word session, then split there to test how the parts connect. Can this first part stand alone? Yes: the words beginning with that explain the assumption, so the first part is a full sentence.
- Step 2
Read past the interruption
What is the subject of proved compelling? The choices give us the evidence, and though initially easy to overlook sits between that subject and its verb. The commas mark the start and end of this interruption, so set it aside while testing whether the rest can stand alone. With its own subject and main verb, the evidence proved compelling is a full sentence.
- Step 3
Check the opening word
Does adding an opening word change the test? Because makes the words about the evidence depend on something else, so the version beginning with Because leaves a fragment, words that can't stand alone as a sentence. The colon after proved compelling: doesn't fix that, because a colon introducing an explanation must follow a full sentence.
- Step 4
Give the sentences a boundary
The version with session, the evidence makes a comma splice, which joins full sentences with only a comma. Session the evidence has no punctuation between them, so it's a run-on. A period separates the full sentences, and session. The evidence, though initially easy to overlook, does that without making the words about the evidence depend on anything else. Choice C.