A punctuation question with the same transition in every choice tests how you separate sentences and set off a linking word. Cover the transition and check whether each side can stand alone. A semicolon or period can separate complete sentences, but a comma alone or no punctuation can't. Then use the meaning to decide which sentence the transition belongs to. An opening transition takes a comma after it; an interrupting transition takes commas on both sides.
Hints
- Hint 1
Cover however and check whether the words on each side of the blank can stand alone. Look for who or what each side is about and what that person or thing does.
- Hint 2
Look for how the later discoveries relate to Pluto’s initial classification. Does the second idea support the first, or go against it?
Step-by-step
Cover, split, and place the transition
Step 1Find the complete sentences
Cover however and read each side of the blank. Can each side stand alone? Astronomers initially classified Pluto tells us who did what, and the rest completes that thought. The discoveries also do something: they have led scientists to reconsider its status. That makes another full thought, so we're joining two complete sentences.
- Step 2
Check the sentence boundary
What can separate those sentences? A transition can't join them by itself, and a comma can't do that job either. The version with a comma before however creates a comma splice, which means complete sentences joined by only a comma. The version with no marks runs the sentences together.
- Step 3
Place the transition
However means but or in contrast, so where does it belong? The discoveries lead scientists to reconsider its status, which contrasts with the earlier classification, so it starts the second sentence. A semicolon can join the complete sentences, and an opening transition needs a comma after it, so the version with a semicolon before however and a comma after it supplies both marks. Choice A.