A punctuation question with the same transition in every choice tests sentence breaks and where the transition belongs. Cover the transition and split the text, then ask whether each side can stand alone. Full sentences need a period or semicolon between them. Set off a transition with a comma at a sentence's start or end, or paired commas in the middle. Then check which ideas the transition links, because its position must fit the meaning as well as the punctuation.
Hints
- Hint 1
Cover however and check whether each side can stand alone. Look for who or what each side is about and what it does.
- Hint 2
Look for how the details about gaps relate to the protection claim. Do those details challenge the claim or help explain it?
- Hint 3
However means but. Compare the ideas linked by each possible position, and ask which ideas the passage sets against each other.
Step-by-step
Split and place the transition
Step 1Find the full sentences
Cover however and split at the blank, keeping the shared words complete in practice with The resulting protection is rarely. Can each side stand alone? The first tells us what the protection is, and gaps where panels meet can guide some of the field inward tells us what the gaps can do. Both are full sentences, so a period or semicolon must separate them; however can't do that job.
- Step 2
Check the break and the commas
Which versions break the punctuation rules? The version with commas around however creates a comma splice, which means two full sentences joined only by a comma. The version with no mark before however leaves out the comma needed when the transition ends a sentence. The version with a semicolon before however leaves out the comma needed when it starts a sentence. The sentence break and the transition's comma do different jobs.
- Step 3
Find the contrast
Does however, meaning but, belong with the details about gaps? Those details and the intense field explain why protection is rarely complete, so they back up that claim instead of turning against it. The contrast comes earlier: engineers describe the enclosure as redirecting an external magnetic field, but its protection has practical limits. However ends the protection claim, with a comma before it; the semicolon after it brings in the reasons that protection falls short. Choice A.