#19 - Lathyrism, a debilitating neurological disorder caused

[srcline@noctrl.edu]

Hello

I am having a hard time understanding why C is the correct answer, I chose B. Since this is a most strongly supported question its like a MBT question in that your basically making an inference correct? I chose B because the of the last sentence of the stimulus, "rats that ingested Lathyrus did not produce the symptoms associated with the disorder. B states that the rats did not consume as much lathyrus as did the domestic animals that contracted lathyrism.

Cant you assume that if something is ingested its consumed?

Also where does the stimulus say that domestic animals are equally susceptible to lathyrism? All it says in the stimulus is that it affects domestic animals.

Thankyou
Sarah

[Robert Carroll]

Sarah,

You are correct that this is a Must Be True. Thus, you must stick with the facts as given in the stimulus, and not add new information.

If something is ingested, it is consumed. That isn't a problem. The problem is that the stimulus claims that rats that ingested Lathryus sativa did not produce the symptoms; answer choice (B) says that the rats did not consume as much Lathryus sativa. The stimulus claims the rats ingested/consumed (the words are relevantly synonymous here, so they are interchangeable) Lathryus sativa, so we know they ingested/consumed some amount, but not how much. Answer choice (B) goes beyond the facts by claiming they ingested/consumed a certain amount that was less than the amount other animals ingested/consumed.

That the rats did not show symptoms does not mean they ate a smaller amount. That would be new information.

The stimulus never says that domestic animals are equally susceptible to lathyrism. In fact, the stimulus implies the opposite, because rats did not show the symptoms, while other domestic animals do, so there has to be some difference in susceptibility between the groups.

Be careful that you don't get an opposite answer with this kind of Must Be True question.

Robert Carroll

[cboles]

Is D incorrect because we are assuming that the rat is not domestic?

I was in between C and D but picked D because there was an emphasis on domestic animals in the stimulus. And answer choice C talks about animal species in general which I thought was too broad.

[Nikki Siclunov]

Hi cboles,

The stimulus asks us to identify a provable claim - something that must be true given the information contained in the stimulus. Do we have proof that most of the animals that can contract lathyrism are domestic? Of course not. Some are, because lathyrism is widespread among the domestic animals of some countries. "Widespread" doesn't mean "most"; furthermore, it's entirely possible that many other animals, except for rats, perhaps, can contract the disease. Thus, answer choice (D) is incorrect.

While the statement in answer choice (C) is indeed broad, we have sufficient proof to validate it. If some animals, such as rats, are not susceptible to the disorder, then clearly not all animals are susceptible to it."Some are not" is logically identical to "not all."

Hope this helps!

[avengingangel]

hey there. i was between c & e and ultimately chose e. can you please explain (further) why c is correct ??

my reasoning as to why e was superior to c was: technically all animal species could be equally susceptible to lathyrism, but it might just depend on the *environamental conditions* (i.e. a person's home VS a laboratory) that that animal species lives in !! so i thought e was the best statement you could choose that is supported by the information given in the stimulus

thanks !!

[Francis O'Rourke]

The stimulus tells us that in some countries this disease is widespread among domestic animals. On the other hand, scientists have generally failed to induce the disease in rats - they do not produce the symptoms when they ingest the legume. So on the one hand we have domestic animals who pick up the disease to a great extent, and on the other hand we have scientists being generally unable to get rats to become infected, presumably after a reasonable amount of effort. From this we can conclude that rats just don't get the disease as easily as the domestic animals mentioned earlier.

We require quite a few more facts before we can infer Answer choice (E) :

• the rats were tested in labs instead of in the field
• other animals were tested in labs and failed to pick up the disease.

Without at least these pieces of knowledge, we cannot claim that the laboratory conditions are to blame for the failure of rats to pick up the disease.

[avengingangel]

Thanks Francis! That's helpful and makes sense.

[lsatnoobie]

Hi, I’m having trouble with getting rid of answer choice D. I chose D because I assumed rats aren’t domestic animals, and since the rats weren’t affected by L, most of the animals that are affected by contracting L are domestic animals.

Maybe I’m confusing the definition of domestic? Can rats be domestic animals as well?

[Adam Tyson]

Rats can indeed be domestic, noobie - my cousin Ben had pet rats, and so do plenty of other folks, and I hear they are actually great pets - but that isn't the point. The point is, can we PROVE that most of the animals that can contract lathyrism are domestic? We know that at least some domestic animals are affected, and we know that at least one animal (rats) is not. We don't know if rats are domestic. We don't know what other animals may be affected and which ones cannot be. Are lions susceptible? Baboons? Walruses? We just don't know! There is nothing that we can prove about "most" here, just about "some" and "not all".

That's the key to answer C, the credited response. We know, from the tests on rats, that not all animals are equally susceptible, because rats don't get the disease while at least some other animals (the domestic ones among which it is widespread) do.

[mollylynch]

I understand why C is right. But if rats had different physiology than domestic animals, would that explain why they did not react?