PSAT Writing and Language Question 686: Answer and Explanation

Question: 686

• A. NO CHANGE
• B. experiment, which demonstrated the existence of antimatter, scientists
• C. experiment; which demonstrated the existence of antimatter, scientists
• D. experiment which demonstrated the existence of antimatter scientists

Correct Answer: B

Explanation:

(B) The sentence can still function as a complete sentence without the phrase "which demonstrated the existence of antimatter." So the phrase should be surrounded by commas to set it aside. Choice (A) does not have a necessary pause before the phrase. Choice (C) does not have the necessary completed sentence before the semicolon. Choice (D) has no pauses whatsoever.