Years of dedicated research finally led to a breakthrough _______ a vaccine with 99% efficacy.
3
readingWhich choice completes the text so that it conforms to the conventions of Standard English?
A
breakthrough,
B
breakthrough;
C
breakthrough:
D
breakthrough—
Correct Answer: D
Choice D is the best answer. This question tests dash usage for dramatic revelation.
- Context clues: What follows dramatically reveals what the breakthrough is.
- Meaning: A dash creates dramatic effect when revealing important information.
- Verify: "...finally led to a breakthrough—a vaccine with 99% efficacy" creates effective drama.
💡 Strategy: Use a dash for dramatic effect when revealing significant information.
Choice A is incorrect because a comma doesn't provide dramatic emphasis. Choice B is incorrect because a semicolon requires independent clauses. Choice C is incorrect because while a colon works, a dash is more dramatic.