5
Answer: ASet 5: Words in Context (Intermediate)
Explanation
PASSAGE
The experiment was designed to isolate the specific variable triggering the reaction, but multiple confounding factors made it difficult to ______ the true cause.
Which choice completes the text with the most logical and precise word or phrase?
A. discern✓ Correct
B. obscure
C. invent
D. guess
Detailed Explanation
Confounding factors make it hard to see or understand the truth. 'Discern' means to perceive or recognize (something).
Key Evidence:
• "difficult to"
• "multiple confounding factors"
Why others are wrong: B (Obscure means to hide, but the factors already did that.), C (Invent means to create.), D (Guess implies not knowing, but the goal was to find out.).