请教prep的一道题

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Which of the following most logically completes the argument?

A new machine for harvesting corn will allow rows to be planted only fifteen inches apart, instead of the usual thirty inches.  Corn planted this closely will produce lower yields per plant.  Nevertheless, the new machine will allow corn growers to double their profits per acre because __________.

(A) with the closer spacing of the rows, the growing corn plants will quickly form a dense canopy of leaves, which will, by shading the ground, minimize the need for costly weed control and irrigation
(B) with the closer spacing of the rows, corn plants will be forced to grow taller because of increased competition for sunlight from neighboring corn plants
(C) with the larger number of plants growing per acre, more fertilizer will be required
(D) with the spacing between rows cut by half, the number of plants grown per acre will almost double
(E) with the closer spacing of the rows, the acreage on which corn is planted will be utilized much more intensively than it was before, requiring more frequent fallow years in which corn fields are left unplanted
答案是A
B为什么不对 

追忆逝去

因为原题没有告诉你CORN的HEIGHT与PROFIT的关系，不一定越高YIELD越大然后PROFIT越大