Five years ago, during the first North American outbreak of the cattle

Question

Five years ago, during the first North American outbreak of the cattle disease CXC, the death rate from the disease was 5 percent of all reported cases, whereas today the corresponding figure is over 18 percent. It is clear, therefore, that during these past 5 years, CXC has increased in virulence.

Which one of the following, if true, most substantially weakens the argument?

(A) Many recent cattle deaths that have actually been caused by CXC have been mistakenly attributed to another disease that mimics the symptoms of CXC.

(B) During the first North American outbreak of the disease, many of the deaths reported to have been caused by CXC were actually due to other causes.

(C) An inoculation program against CXC was recently begun after controlled studies snowed inoculation to be 70 percent effective in preventing serious cases of the illness.

(D) Since the first outbreak, farmers have learned to treat mild cases of CXC and no longer report them to veterinarians or authorities.

(E) Cattle that have contracted and survived CXC rarely contract the disease a second time.

Bunuel · Accepted Answer

OFFICIAL EXPLANATION

(A) No. This substantially strengthens the argument. If many recent deaths due to CXC have been mistakenly attributed to another disease, then the 18 percent death rate would be even higher.

(B) No. This substantially strengthens the argument. If many of the deaths reported to have been caused by CXC were actually due to other causes, then the 5 percent initial death rate would be lower. Hence, the increase in virulence would be even greater.

(C) No. This choice is irrelevant. The effectiveness of an inoculation program has no bearing on the virulence of a disease. Inoculations are used to prevent infection by a disease. However, once infected, the disease’s virulence measures the severity of the sickness. The fact that a disease can often be prevented does not affect its virulence if caught.

(D) Yes.  If the mild cases are no longer reported, then the serious cases would be disproportionately represented. For example, suppose of 100 cattle with the disease, 73 have a mild case, 27 have a serious case and 5 will die of the disease. Then the death rate would be 5 percent. Now, if the 77 cattle with mild cases are not considered, then the reported death rate would be approximately 18 percent: 5/27 ≈ 18%.

(E) No. The passage is about the virulence of the disease, not about an animal’s immunity to a second infection.

saicharan1191 · Answer

Imo clear D. The death percentage increased because of the decrease in the number of cases reported. 
A and B strengthen the argument.

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kunalsinghNS · Answer

We need to find an argument that weakens the conclusion - "It is clear, therefore, that during these past 5 years, CXC has increased in virulence."

(A) Many recent cattle deaths that have actually been caused by CXC have been mistakenly attributed to another disease that mimics the symptoms of CXC. -  If we correct the mistake in this argument then we can see that CXC actually increases the number of deaths. hence, its a strengthener

(B) During the first North American outbreak of the disease, many of the deaths reported to have been caused by CXC were actually due to other causes. -  This option talks about the death caused by CXC but we dont know the size of the infected population

(C) An inoculation program against CXC was recently begun after controlled studies snowed inoculation to be 70 percent effective in preventing serious cases of the illness. -  Irrelevant

(D) Since the first outbreak, farmers have learned to treat mild cases of CXC and no longer report them to veterinarians or authorities. - If the famers dont report the mild cases whereas the severe ones causes the same amount of deaths. This leads to a fall in total number of reported cases.  hence, Correct.

(E) Cattle that have contracted and survived CXC rarely contract the disease a second time. - Irrelevant

srikanth9502 · Answer

Suppose, a total of 100 hundred cattle were effected by CXC during its initial outbreak and 5 of them died. In this case the death percentage is 5%

After 5 years even if 100 cattle are effected by the disease and if only 70 are reported to the authorities because the balance 30 had mild syptoms of the disease. Now even if the same number i.e 5 cattle die, the death rate increases as the total number of only 70 cattle are taken into consideration to calculate the death rate.

This weakens the argument's conclusion that the disease has grown in virulence.

udaypratapsingh99 · Answer

if in first outbreak no. of cases were 5000 and all were reported then actual death were 250(5% of 5000)
and if suppose 360 deaths happened in recent outbreaks out of 2000 reported cases then indeed % of deaths > then 1st outbreak, however if another 2000 cases, which are not reported as said by option D then the figure would have been 9% , a figure lower then prev.
Hence option D weakens it

unraveled · Answer

Five years ago, during the first North American outbreak of the cattle disease CXC, the death rate from the disease was 5 percent of all reported cases, whereas today the corresponding figure is over 18 percent. It is clear, therefore, that during these past 5 years, CXC has increased in virulence.

Which one of the following, if true, most substantially weakens the argument?

(A) Many recent cattle deaths that have actually been caused by CXC have been mistakenly attributed to another disease that mimics the symptoms of CXC. - WRONG. Changes the perspective of passage altogether.

(B) During the first North American outbreak of the disease,  many of the deaths reported  to have been caused by CXC were actually  due to other causes . - WRONG. Out of scope.

(C) An inoculation program against CXC was recently begun after controlled studies snowed inoculation to be 70 percent effective in  preventing serious cases of the illness . - WRONG. Irrelevant.

(D) Since the first outbreak, farmers have learned to treat mild cases of CXC and no longer report them to veterinarians or authorities. - CORRECT. If reporting gets less then percentage of death increase. Thus, virulence is actually unchanged almost.

(E) Cattle that have contracted and survived CXC  rarely contract the disease a second time . - WRONG. Goes against the conclusion. What about the deaths?

Answer D.

Tejasethb · Answer

A -This will strengthen the argument- if CX C has been mistakenly attributed to another disease, that means the number of people who died due to CX is more today, and we need to show that the number is actually less. A
B - Same this word, strengthen the argument because if the actual case of death of CX were overly reported previously, that means previous number is less, but we need to show that the difference between the previous and the current has not enlarged for weakening the argument, but if previous number is less, then that word, find the difference between the current and the previous figure. B
C-This won't impact the argument-
D- If the mild cases are under reported that means out of all the cases reported, the major were only the more severe ones that is now the 18% figure is actually the figure which shows out of more severe ones. For example, earlier, there were hundred cases reported and out of that 5% that is five were causing death.

Five years ago, during the first North American outbreak of the cattle

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Five years ago, during the first North American outbreak of the cattle

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