The James Webb Space Telescope _______ launched in December 2021 _______ has revolutionized our understanding of the universe.
1
readingWhich choice completes the text so that it conforms to the conventions of Standard English?
A
which was launched in December 2021
B
, which was launched in December 2021,
C
—which was launched in December 2021
D
, which was launched in December 2021—
Correct Answer: B
Choice B is the best answer. This question tests comma usage with nonrestrictive clauses.
- Context clues: There's only one James Webb Space Telescope, so the clause is nonessential.
- Meaning: Nonrestrictive clauses with "which" are set off by commas on both sides.
- Verify: "The James Webb Space Telescope, which was launched in December 2021, has revolutionized..." correctly adds extra information.
💡 Strategy: Unique proper nouns take ", which" clauses with commas on both sides.
Choice A is incorrect because it lacks commas. Choice C is incorrect because a single dash creates asymmetry. Choice D is incorrect because it mixes comma and dash.