Gortland has long been narrowly self-sufficient in bothgrain and meat. However, as per capita income in Gortland has risen toward theworld average, per capita consumption of meat has also risen toward the worldaverage, and it takes several pounds of grain to produce one pound ofmeat. Therefore, since per capita incomecontinues to rise, whereas domestic grain production will not increase,Gortland will soon have to import either grain or meat or both.
Which of the following is an assumption on which theargument depends?
(A) The total acreage devoted to grain production inGortland will soon decrease.
(B) Importing either grain or meat will not result in asignificantly higher percentage of Gortlanders' incomes being spent on foodthan is currently the case.
(C) The per capita consumption of meat in Gortland isincreasing at roughly the same rate across all income levels.
(D) The per capita income of meat producers in Gortlandis rising faster than the per capita income of grain producers.
(E) People in Gortland who increase their consumption ofmeat will not radically decrease their consumption of grain.
思路：结论：Gortland will soon have toimport either grain or meat or both
原因：per capita incomecontinues to rise, whereas domestic grain production will not increase
B: 否定句。但是进口谷物/肉会不会导致更高比例收入花在食物上，没有加强最终的结论“Gortland will soon have to import either grain or meat orboth”;