大全-18-10

10.   urebred
cows native to Mongolia produce, on average, 400 liters of milk per year; if
Mongolian cattle are crossbred with European breeds, the crossbred cows can
produce, on average, 2,700 liters per year. An international agency plans to
increase the profitability of Mongolia’s dairy sector by encouraging widespread
crossbreeding of native Mongolian cattle with European breeds.

Which of the following, if true, casts the
most serious doubt on the viability of the agency’s plan?

(A) Not all
European breeds of cattle can be successfully bred with native Mongolian
cattle.

(B) Many young
Mongolians now regard cattle raising as a low-status occupation because it is
less lucrative than other endeavors open to them.

(C) Mongolia’s
terrain is suitable for grazing native herds but not for growing the fodder
needed to keep crossbred animals healthy.

(D) Cowhide and
leather products, not milk, make up the bulk of Mongolia’s animal product
exports to Europe.（C）


(E) Many European
breeds of cattle attain average milk production levels exceeding 2,700 liters.


答案是C，但大家不觉得E更加有理么？

前提已经说了，可以杂交成功。前提事实不可以被评价的！

请执教！！

A为什么不对？