Substances suspected of causing cancer, if carefully administered to e

Question

Substances suspected of causing cancer, if carefully administered to experimental animals in quantities in which those substances are ordinarily present in the environment, are virtually guaranteed not to produce cancer at rates significantly above the chance level. The most economical procedure for obtaining informative data is to administer vastly increased amounts of the substance being tested.
 
The 'economical procedure' described above will not be an effective one if which of the following is true?

(A) Cancer data on experimental animals yield accurate estimates of the risk of cancer for human beings. 
(B) Experimental animals will often develop cancer in response to receiving excessive quantities of a substance, regardless of the specific properties of the substance. 
(C) When more of a possibly cancer-causing substance is administered to experimental animals, fewer animals are needed for significant data to be obtained. 
(D) Among experimental animals, the chance level for many types of cancer is virtually zero. 
(E) Substances will often be tested in amounts greater than necessary to obtain informative data.

Kudos  for the OA and explanation

arvind910619 · Answer

So we have to weaken the question 
If monitored doses are administered then the chance of getting cancer are no higher than by natural chance. So to make economical sense increase the dosage of the substances known to to cancer. We have to attack this statement and show that increased dosage will not case anything or will have general outcome as opposed to specific outcome desired.
B hits the bull's eye and it out answer

nedunurianurag · Answer

arvind910619

Hi. Can you explain how this is a weaken question. There is no conclusion in the argument. This is a must be true question according to me.

kunaldutt15 · Answer

Substances suspected of causing cancer, if carefully administered to experimental animals in quantities in which those substances are ordinarily present in the environment, are virtually guaranteed not to produce cancer at rates significantly above the chance level. The most economical procedure for obtaining informative data is to administer vastly increased amounts of the substance being tested.

The 'economical procedure' described above will not be an effective one if which of the following is true?

Conclusion: The most economical procedure for obtaining informative data is to administer vastly increased amounts of the substance being tested.
We can weaken this conclusion by showing that increasing the dose will not be fruitful.

(A) Cancer data on experimental animals yield accurate estimates of the risk of cancer for human beings.
  Irrelevant. This does not harm the conclusion in any way.

(B) Experimental animals will often develop cancer in response to receiving excessive quantities of a substance, regardless of the specific properties of the substance.
  This is definitely a weakener. It tells us that the "economical procedure" will not be an effective one since the doctors won't be able to test the specific properties of the substance induced. CORRECT.  
 
(C) When more of a possibly cancer-causing substance is administered to experimental animals, fewer animals are needed for significant data to be obtained.
  This tells us how the method is more economical in the sense that we would require fewer test animals if we increase the dose to get significant data. This does not weaken the argument. In fact, its a strengthener.

(D) Among experimental animals, the chance level for many types of cancer is virtually zero.
  Irrelevant.

(E) Substances will often be tested in amounts greater than necessary to obtain informative data.
  This option, if anything, is a strengthener.

nedunurianurag · Answer

Awesome. Nice explanation. How are you certain that the statement you indicated is the conclusion. Can you please elaborate? As far as my understanding goes, I perceived the statements as mere facts. Also, there was no conclusion indicator present.

arvind910619 · Answer

Hi nedunurianurag

Here is the question stem.

The 'economical procedure' described above will not be an effective one if which of the following is true?

The meaning of the question stem is that it wants us to find out which of the options available will make the argument weak. 
Here it is asking us to find a flaw in the plan that is one way of saying weaken the argument.
 
Hope it helps

mSKR · Answer

B and D seems to be polar opposite.

If i think as if experimental animals get cancer then it means dosage worked as expected and we can have accurate measurements

But D says, even dosage is increased , chances are still zero . it means we can't measure any effect.

carcass   mira93 ,  nightblade354 ,  eakabuah

Then why not D is answer?
i am confused, why it is otherwise in terms of cancer chances.

nhatanh811 · Answer

I initially chose D as well and did not understand why B is correct. This is my thought after thinking about it for a while.

B is the weakener because, in order for the economical procedure to be effective, it has to provide informative data, aka whether the suspected substances cause cancer or not and which ones do. In B, regardless of the substance, as long as the quantities are excessive, the animals will develop cancer. It implies that even substances that normally do not cause cancer will also cause cancer in excessive quantities, hence the data is not informative.

D is not the weakener because of the word "many". Just because many types of cancer have zero chance to develop in experimental animals, it does not mean that the procedure is not effective in identifying the remaining substances that cause cancer. I also did not see the substance mentioned here so that is a flag.

Experts, if you can give me some feedback on my reasonings, it would be great! Thanks.

himani007 · Answer

Substances suspected of causing cancer, if carefully administered to experimental animals in quantities in which those substances are ordinarily present in the environment, are virtually guaranteed not to produce cancer at rates significantly above the chance level. The most economical procedure for obtaining informative data is to administer vastly increased amounts of the substance being tested.

The 'economical procedure' described above will not be an effective one if which of the following is true?

Conclusion: The most economical procedure for obtaining informative data is to administer vastly increased amounts of the substance being tested.
We can weaken this conclusion by showing that increasing the dose will not be fruitful.

(B) Experimental animals will often develop cancer in response to receiving excessive quantities of a substance, regardless of the specific properties of the substance.
  This is definitely a weakener. It tells us that the "economical procedure" will not be an effective one since the doctors won't be able to test the specific properties of the substance induced. CORRECT.

(D) Among experimental animals, the chance level for many types of cancer is virtually zero.
  Irrelevant.

Why will option (D) be irrelevant? It can also contribute to what is being asked in the question.

VerbalBot · Answer

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Substances suspected of causing cancer, if carefully administered to e

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