To reduce the danger to life and property posed by major earthquakes

To prevent damages caused by earthquakes, scientists will rely on catfish because they swim erratically before earthquakes.

Which of the following, if true, most seriously undermines the usefulness of the proposal?

We have to look for an answer that undermines the connection earthquake => movement of catfish.
E does just that:
(E) Even very slight, fleeting tremors cause catfish to swim erratically
The connection in undermined now

Initially I was quite sure of C, so I want to explain why I discarded it eventually:
(C) Tremors lead to the release of hydrogen sulfide gas into water, thereby causing various fish and shellfish to behave erratically.
The text talks about catfish and not about "various fish", we cannot say anything about catfish.

well i think all the choices but E are helping to explain as why this plan can work
E sud be the answer coz conclusion is abt the dangerous earthquakes but E tells us that even minor tremors can cause these fish to behave erratically !! so the plan is useless

Hi Zarr,

Choice (E) Even very slight, fleeting tremors cause catfish to swim erratically

Can't we infer that in case of dangerous earthquakes, definitely the cat fish would SWIM erratically?

And hence the proposal of monitoring the CATFISH to predict dangerous earthquakes is strengthened rather than weaken.

My 2 cents, I think answer lies within the story "The Boy Who Cried Wolf"
Joke apart.. idea is to find a reliable solution for giving advance warning abt dangerous earthquakes to people.
Now if scientists are relying on a source, which behaves similarly in 2 different situations then how would they decide whether its time to alert ppl abt the major earthquake or not.
Hope this answered your query and didn't create further confusion

Argument talking about dangerous earthquake and E undermines this argument saying that its not accurate and misleading.

Answer: E

I think C at first looks very obvious, but the wording the answer choice involves is tricky. It says that Tremors lead to release of Hydrogen Sulfide..... This is a trap.... we have to assume here that scientists have no method to find the release H2S gas. Then and then only we can move forward. This assumptions makes this choice wrong and also the fact that other fish behave erratically is Inconsistent.

(A) In Japan, which is subject to frequent earthquakes, the behavior of catfish has long been associated with earthquakes. Strengthener

(B) Mechanical methods for detecting earthquakes have not proved effective. Out of scope

(C) Tremors lead to the release of hydrogen sulfide gas into water, thereby causing various fish and shellfish to behave erratically. Out of scope

(D) Careful construction can reduce the dangers posed by earthquakes. Out of scope

(E) Even very slight, fleeting tremors cause catfish to swim erratically. Correct.
_________________

Correct me if I'm wrong

I think if we consider what option E is saying, even a small tremor can cause the catfish to swim erratically. This will make the system even more precise as the system will be able to detect even a very small earthquake. This will strengthen the authors claim.

Please help me understand where I'm going wrong.

The question says: Catfish swim erratically before earthquakes, some investigators have proposed monitoring catfish to predict dangerous earthquakes.

To undermine the saying, you have to prove that there may be some other reasons, besides than earthquakes, that can cause catfish swim erratically.

Therefore:
(A) In Japan, which is subject to frequent earthquakes, the behavior of catfish has long been associated with earthquakes. (Act as an example that agree with and strengthen the saying)
(B) Mechanical methods for detecting earthquakes have not proved effective. (No any mechanical method mentioned. Out of scope)
(C) Tremors lead to the release of hydrogen sulfide gas into water, thereby causing various fish and shellfish to behave erratically. (Do not necessarily related to Catfish. Out of Scope)
(D) Careful construction can reduce the dangers posed by earthquakes. (Not related to catfish. Out of Scope)
(E) Even very slight, fleeting tremors cause catfish to swim erratically. (Suggest another reason that causes catfish to swim erratically, besides than earthquakes. -> Correct)

My mistake was that I assumed that "various fish" should somehow include the catfish. But the key to this question actually lies in the question itself: usefulness of the plan. The pan is to reduce the danger to life and property posed by major earthquakes. So a technique that is too sensible will arguably be useful.

The plan is to use erratically swimming to predict DANGEROUS earthquakes, and we have to show that using erratically swimming would not help to predict DANGEROUS earthquakes

We have to special ettention to the wording: even one word can play a significant role.

weakener 1: plan must predict correctly, otherwise it cannot work. If catfish are so sensitive that even slight shocking can cause them to swim erractically, then plan would not be realiable: Remember that we are concerned about DANGEROUS earthquakes

weakener 2: what if catfish also swim erratically because of other reasons, apart from earthqueakes: For example, When temperature is low.

(A) In Japan, which is subject to frequent earthquakes, the behavior of catfish has long been associated with earthquakes.

1) This answer choice can actually reinforce the argument or plan above, showing that there are a relationship between earthquakes and the behavior of catfish. Yet, this choice would be a clear strengthener if it talked about DANGEROUS earthqueakes.

(B) Mechanical methods for detecting earthquakes have not proved effective.

1) irrelevant

(C) Tremors lead to the release of hydrogen sulfide gas into water, thereby causing various fish and shellfish to behave erratically.

1) the plan is concerned about catfish, so other fish are irrelevant

(D) Careful construction can reduce the dangers posed by earthquakes.

1) That there are other plans to reduce the dangers posed by earthquakes is not going to weaken:

(E) Even very slight, fleeting tremors cause catfish to swim erratically

1) weakener 1: Catfish can be caused to swim erratically by even slight earthquakes, with the result that some predictions cannot be reliable.

An easy to understand argument: earthquakes have to be predicted beforehand. Catfish is known to swim erratically before earthquakes, so observing them can help in making predictions.

We have to weaken this proposal. So we need to find some flaw with the catfish behavior such that we get a hint that catfish might not turn out to be as useful as we are thinking.

I could not come up with any such scenario in mind, but had this above idea in mind before moving to options :

(A) In Japan, which is subject to frequent earthquakes, the behavior of catfish has long been associated with earthquakes.
If this is the case, then it makes me believe more in the proposal. If Japan has seen this behavior for a long time, we might say, oh yes then its sort of good, perhaps we can go ahead with the proposal. Incorrect choice.

(B) Mechanical methods for detecting earthquakes have not proved effective.
This option only tells us that one class of methods is not very effective. In other words, we should be looking at non-mechanical methods of detection. But this idea does not focus on what we have in front us : can catfish be used as method of detection ??.... perhaps it can be , or perhaps it can't be. No impact whatsoever. So, incorrect choice.

(C) Tremors lead to the release of hydrogen sulfide gas into water, thereby causing various fish and shellfish to behave erratically.
This option tells us why fishes behave erratically when tremors occur. It links the behavior to tremors, so makes me say to myself : okay, at-least there exists a link between the behavior of fishes and the timing of tremors, that too a favorable one.
It acts as a strengthener. So incorrect choice.

(D) Careful construction can reduce the dangers posed by earthquakes.
This option simply tells us how we can reduce dangers posed by earthquakes. But how does this statement show us the catfish can be or cannot be used for detection ?.... There exists no link whatsoever, so incorrect choice .

(E) Even very slight, fleeting tremors cause catfish to swim erratically
This option links tremors to catfish behavior directly . But it tells us that even very weak tremors can lead to that behavior. If that is the case, can we trust the catfish at all ?
What if a boat or ship passes by catfish ?
Will it not behave erratically then?...
So does a ship passing by mean earthquake is probable ?
This sensitive nature of catfish only makes it look useless for detection.
This option weakens the proposal and is the correct choice.

Correct choice is E

To reduce the danger to life and property posed by major earthquakes, scientists have been investigating several techniques for giving advance warning of dangerous earthquakes. Since catfish swim erratically before earthquakes, some investigators have proposed monitoring catfish to predict dangerous earthquakes.
Conclusion: some investigators have proposed monitoring catfish to predict dangerous earthquakes.
Which of the following, if true, most seriously undermines the usefulness of the proposal?


(A) In Japan, which is subject to frequent earthquakes, the behavior of catfish has long been associated with earthquakes.if anything, this strengthens the argument.

(B) Mechanical methods for detecting earthquakes have not proved effective.no where in the passage mentioned mechanical methods. we cannot say that mechanica methods have not proved effective - this does not weaken the argument.

(C) Tremors lead to the release of hydrogen sulfide gas into water, thereby causing various fish and shellfish to behave erratically. this one is tricky. keep in mind, we are only concerned with catfish, not various fish and shellfish

(D) Careful construction can reduce the dangers posed by earthquakes. we are not talking about reducing the dangers posed by earthquake, we are talking about giving advance warning.

(E) Even very slight, fleeting tremors cause catfish to swim erratically absolutely weakens the argument. if the slightest tremor causes catfish to swim erratically, they will be swimming erratically regardless of tremor of any magnitude. Thus, this weakens the argument.

Let me talk about option C.

The point of the argument is that we're trying to predict earthquakes by monitoring catfish.

Option C essentially tells us HOW earthquakes lead catfish to behave erratically - by releasing hydrogen sulfide gas into water.

However, the "how" does not matter as long as catfish behaved erratically before the earthquake. Of course, in light of option C, we can also probably predict earthquakes by looking at the release of hydrogen sulfide in water. However, the presence of an alternate way doesn't weaken our way of predicting earthquakes.