Todays farmers plant only a handful of different strains of a given

Question

Today’s farmers plant only a handful of different strains of a given crop. Crops lack the diversity that they had only a few generations ago. Hence, a disease that strikes only a few strains of crops, and that would have had only minor impact on the food supply in the past, would devastate it today.

Which one of the following, if true, would most weaken the argument?

(A) In the past, crop diseases would often devastate food supplies throughout entire regions.

(B) Affected crops can quickly be replaced from seed banks that store many strains of those crops.

(C) Some of the less popular seed strains that were used in the past were more resistant to many diseases than are the strains popular today.

(D) Humans today have more variety in their diets than in the past, but still rely heavily on cereal crops like rice and wheat.

(E) Today’s crops are much less vulnerable to damage from insects or encroachment by weeds than were crops of a few generations ago.

Bunuel · Accepted Answer

EXPLANATION FROM Fox LSAT

This argument presents some evidence about lack of diversity in today’s crops (unlike the diverse crops of the past) and how this means that a single disease that attacks only a few strains of crops might have a big impact. The argument then concludes that if this happened then the food supply could be “devastated.”

We are asked to weaken the question. To argue with this speaker, we should try to put a wedge in between the evidence and the conclusion. Would the food supply really be  devastated ? Hmm. What if we had a lot of food stored up, like five years' worth of Spam, fruit cocktail, and pork and beans? If that were true, wouldn’t we have plenty of time to plant new crops if a disease struck? It might be gross, but the food supply wouldn’t be devastated.

That’s probably not going to be exactly the answer, but we’re looking for something that would similarly cause the argument’s conclusion to fail, even in the event of crop disease.

A) If this is true, it would only strengthen the idea that today’s food supply is fragile. So this isn’t a good weakener.

B) This is a weakener. If seed banks can “quickly” replace any crops that get lost to disease, then the food supply is probably not at risk. I hope C, D, and E are terrible because I’d love to pick B.

C) This is a strengthener, not a weakener.

D) We could read this as either a strengthener or a weakener, but we’re looking for a clear weakener.

E) Insects and weeds are irrelevant. The argument was about loss of crops to  disease , so this fact would do nothing to the argument.

B is our answer.

Nidzo · Answer

(A) Does not weaken the argument at all. If anything it may strengthen the view that if even with greater diversity disease could devastate food supplies, then with far less diversity it could be far worse.  Incorrect

(B) Weakens the argument. This tells us that plants can quickly be replaced and that the food chain would not be devastated.  Correct 
 
(C) Strengthens the argument.  Incorrect

(D) Our diets in the past and now are entirely irrelevant to the argument.  Incorrect

(E) The argument's focus is on disease and not insects or encroachment by weeds.  Incorrect

Answer B

Sumi1010 · Answer

Indeed a good problem!
The problem makes you to think every nuance of what-is-given and to what extent you should stay in the "scope" of the problem.

Let's say the farmers grow only A and B strains of the crops. 
In the earlier generation, they used to to grow A,B, C, D and E strains. 
The argument says that since the likelihood of the disease to attack on some strains is more than that on others, the disease would be devastating.

Prethink : 
The argument is right if the current strains are actually more likely to be attacked (note that the argument just talks about "few" strains and not about specific strains grown currently).

What if - the currently grown strains are not those few strains that are more likely to be attacked by the disease ? 
Then, the current strains are safer and the argument is weakened.

What if - the few strains (A and B) that are attacked are easily replaceable by other strains (C and D) as and when the impact of the disease is known?
 Still, the current crops are safer (even with fewer strains).

Now, look at the choices -

(A)  In the past , crop diseases would often devastate food supplies throughout entire regions.
 Half (one-sided) information.  Beware of the trap!  Don't assume about the current situation (from the information on the past)
 How about now? Do the crop diseases devastate limited regions?   
(B) Affected crops can  quickly be replaced  from seed banks that store many strains of those crops.
 If so, the current crops are safer (even with fewer strains as the affected ones have been replaced). 
Weakens the claim that current crops are more devastated by the disease.  
(C)  Some  of the less popular seed strains that were used  in the past   were more resistant  to many diseases than are the strains popular today.
 Read it closely. 
Less popular strain of past VS Popular strains of today. 
Can we conclude anything? Not at all, until we know the relation between the "less popular of past" and "popular of today".

If the two were same set of strains , then we can say past crops were more resistant. 
This actually strengthen the argument. 
(D) Humans today have  more variety in their diets  than in the past, but still rely heavily on cereal crops like rice and wheat.
 Variety of diet - has nothing to do with strains.  
(E) Today’s crops are much less vulnerable to damage  from insects or encroachment  by weeds than were crops of a few generations ago.
 Possible, But don't go beyond the scope of the argument. 
The argument is all about the impact of the disease on the crops. It maybe be true that insects too make the similar impact, but this won't change the impact of the disease.

IMO  B

sivatx2 · Answer

Farmers are using only 10/100 strains of a crop.
Crops has less diversity now. 
If few strains on the 10 strains is infected by disease, means => devastation of food supply, today, when compared to past.

We now have to prove that there is no devastation of food supply - to weaken.

(A) In the past, crop diseases would often devastate food supplies throughout entire regions. 
 We need a proof that today there is no devastation. This option talks only about the past and does not weaken. Eliminate

(B) Affected crops can quickly be replaced from seed banks that store many strains of those crops. 
 This options prevents crops from devastation and hence, weakens the argument. Keep.

(C) Some of the less popular seed strains that were used in the past were more resistant to many diseases than are the strains popular today. 
 This option does not provide information how the devastation of crops can be prevented today. Eliminate

(D) Humans today have more variety in their diets than in the past, but still rely heavily on cereal crops like rice and wheat. 
 This option is irrelevant to the devastation of crops and how it can be prevented today. Eliminate

(E) Today’s crops are much less vulnerable to damage from insects or encroachment by weeds than were crops of a few generations ago. 
 Insect damage/weed encroachment of the past are irrelevant to the argument. Eliminate

So, Option B is the correct answer choice.

VerbalBot · Answer

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Todays farmers plant only a handful of different strains of a given

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