Let's jot down the points:
Premise: B feeling J since for last 3 weeks.
Premise: B working double shift so having 6-7 cups of coffee than usual 2-3cups.
Premise: J hampering work efficiency
Conclusion:Stop drinking coffee to stop J
As to the question, it is implied that there will be 4 weakners, so we need to find that 5th option that would either strengthen or have no relevance with the argument.
Probable answer: We can weaken by saying that it's not coffee but the excess work is affecting B's work efficiency.
A. the jitters may be due to lack of sleep, not excessive caffeine.
INCORRECT. Weakens the argument. Similar to the probable answer.
B. the jitters may be worsened by her total withdrawal from caffeine.
INCORRECT. Weaken. Since she was having extra work and having extra coffee, stopping consumption of coffee might make the condition worse, just like in real life when you stop an addiction, you feel discomfort and distracted.
C. Brianais has never had the jitters before.
CORRECT. I chose this option after cancelling out 4 weakners. This sentence makes sense. If B never had , it's strange she's getting it now. She must fo something. This doesn't affect the argument IMO.
D. Brianais only gets the jitters when she drinks too much coffee.
INCORRECT. A contender. But if you look keenly in the sentence, it says she gets jitters only when she has too much coffee. So the sentence is suggesting us that if she cuts foen her coffee intake, everything will be fine. This weakens the argument which says coffee must be stopped altogether.
E. the jitters may be caused by anxiety due to personal problems or stress at work.
INCORRECT. If jitters are due to personal problem, why stop coffee? Simple weakner.
Now, I am confident that the answer is option C after POE.
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