PSAT Writing and Language Question 539: Answer and Explanation

Question: 539

• A. NO CHANGE
• B. among
• C. within
• D. for

Correct Answer: C

Explanation:

(C) When paraphrased, the clause becomes "I operated inside a balanced cycle," or "I -operated as part of a balanced cycle." Choice (A), "between," requires operating between two things. Choice (B), "among," requires operating among three or more things. However, carbon is part of only one thing: as the cycle. Choice (D) implies a causal relationship that is not logical.