5
Answer: ASet 2: Words in Context
Explanation
PASSAGE
Antibiotics are powerful drugs used to treat bacterial infections, but overuse can lead to resistance, making the medication ______ against future illnesses.
Which choice completes the text with the most logical and precise word or phrase?
A. ineffective✓ Correct
B. potent
C. helpful
D. mandatory
Detailed Explanation
If bacteria become 'resistant' to a drug, the drug no longer works. Therefore, it becomes 'ineffective'.
Key Evidence:
• "resistance"
• "drugs ... treat"
Why others are wrong: B (Potent means powerful, which is the opposite of being resisted.), C (Helpful means useful, but resistance makes them not useful.), D (Mandatory means required, which is unrelated to efficacy.).