gmat 逻辑题

题目

gmat 逻辑题
The price of maple syrup has jumped from 22 dollars three years ago to 40 dollars a gallon today.It can be concluded that maple-syrup harvesters have been artificially inflating prices and that governmental price regulations are necessary to control rising prices.Which of the following,if ture,casts the most doubt on the conclusion drawn above?
（A） The government already requires maple-syrup harvesters to submit their facilities to licensing by the health department.（B） Insect infestation and drought have stunted the growth of syrupproducing maple trees and caused less-abundant syrup harvests.
（C） Maple syrup is produced in rural areas that suffer from high unemployment.
（D） Technological improvements in maple-syrup harvesting have reduced production costs.
（E） Maple-syrup prices have risen many times in the past,though never before at the rate recently observed.

答案

选B这是削弱题型中的BA型（先说结论→再说原因）.这种题型的答案有两中,一种是C→B,即另一个原因导致结果的发生,另外一种是A→非B,即原因结论不匹配,这道题属于前者.A：政府已经采取措施并没有削弱B：是另外的原因（...