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 __________.
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
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
with the larger number of plants growing per acre, more fertilizer will be required
with the spacing between rows cut by half, the number of plants grown per acre will almost double
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
D只是简单重复了原文内容,而且单纯靠从D出发,只能知道“种植数量”将近翻番,而文中又提到说“单株产量”会下降,所以总产量不能够double,自然也推不出Profit能double。
相较而言,A中的推理则是在D的基础上进一步说明,在总产量不能double的情况下,我们又降低了其他费用。那么A的Profit就要比D更高,D的Porfit不可能double,而A的就有double的可能了。
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