Ferber's Syndrome

[komal]

Which of the following most logically completes the argument?

Ferber's syndrome, a viral disease that frequently affects cattle, is transmitted to these animals through infected
feed. Even though chickens commercially raised for meat are often fed the type of feed identified as the source
of infection in cattle, Ferber's syndrome is only rarely observed in chickens. This fact, however, does not
indicate that most chickens are immune to the virus that causes Ferber's syndrome, since ____ _

(A) chickens and cattle are not the only kinds of farm animal that are typically fed the type of feed liable to be
contaminated with the virus that causes Ferber's syndrome

(8) Ferber's syndrome has been found in animals that have not been fed the type of feed liable to be
contaminated with the virus that can cause the disease

(e) resistance to some infectious organisms such as the virus that causes Ferber's syndrome can be acquired
by exposure to a closely related infectious organism

(D) chickens and cattle take more than a year to show symptoms of Ferber's syndrome, and chickens
commercially raised for meat, unlike cattle, are generally brought to market during the first year of life

(E) the type of feed liable to be infected with the virus that causes Ferber's syndrome generally constitutes a
larger proportion of the diet of commercially raised chickens than of commercially raised cattle

OA [spoiler](D)[/spoiler]

[fibbonnaci]

'since' is a premise indicator. the conclusion - just because chickens dont get affected with Ferber's syndrome does not indicate that most chickens are immune to the virus.

you need to provide a reson for this conclusion to rest perfectly.
A word of caution: Notice that the argument specificakky mentions chicken commercially raised for meat.

with this arsenal Lets look at options:

(A) chickens and cattle are not the only kinds of farm animal that are typically fed the type of feed liable to be contaminated with the virus that causes Ferber's syndrome [we are bothered about why chickens dont contract the disease. we are not bothered about other animals. Eliminated!]

(8) Ferber's syndrome has been found in animals that have not been fed the type of feed liable to be
contaminated with the virus that can cause the disease [this is again out of scope. we are talking about the feed that is liable as a source of the disease and it not affecting chickens in particular. Eliminated!]

(e) resistance to some infectious organisms such as the virus that causes Ferber's syndrome can be acquired
by exposure to a closely related infectious organism [does this answer why chickens raised for meat do not contract the disease? do we know that chickens got exposed to closely related infectious organisms? Eliminated!]

(D) chickens and cattle take more than a year to show symptoms of Ferber's syndrome, and chickens
commercially raised for meat, unlike cattle, are generally brought to market during the first year of life [Bingo! this perfectly explains why they dont contract the disease. they are killed for meat even before the disease sets in.]

(E) the type of feed liable to be infected with the virus that causes Ferber's syndrome generally constitutes a
larger proportion of the diet of commercially raised chickens than of commercially raised cattle [this does not answer the question at all. if the chickens feed is liable to be affected with the virus to a greater extent than the feed of cattle, then why is it does chicken does not contract the disease? Eliminated!]

Hope this helps!