QUESTION TEXT: In a recent study of stroke patients, those who…
QUESTION TYPE: Strengthen
CONCLUSION: The leakage of glutamate from nerve cells is a cause of long term brain damage from strokes.
REASONING: Glutamate can harm nerve cells if it leaks.
ANALYSIS: This is a complicated question. There are at least two gaps in the argument.
- The author hasn’t shown that elevated glutamate after a stroke comes from leakages in the brain. The author only said glutamate damages nerve cells when it leaks. If glutamate is elevated for other reasons (e.g. diet) it might be harmless.
- The author hasn’t shown that strokes lead to glutamate leakage. It’s possible a third factor causes both glutamate leakage and strokes.
The right answer patched over the first weakness: it shows that elevated glutamate comes from leakages.
- It doesn’t matter what other neurotransmitters do. The argument is only talking about glutamate, and we already know that glutamate can damage nerve cells.
- It doesn’t matter if other chemical levels are unusual after a stroke. The argument could work even if glutamate is the only unusual chemical.
- It doesn’t matter what other neurotransmitters do. So this answer adds nothing as we already knew glutamate can leak.
- CORRECT. This doesn’t prove the argument correct, but it strengthens it. It eliminates the possibility that glutamate is elevated due to a different reason, such as a dietary excess of glutamate. This therefore shows that excess glutamate can cause damage in the brain because it’s leaking from cells in the brain.
- This doesn’t matter. Not all nerve cells are going to leak glutamate at once. So glutamate could leak from cells that die, and then that glutamate could harm other living cells.
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