Explanation
Correct answer: A.
Choice A is the best answer because it presents the conclusion that most logically completes the text’s discussion about a trade-off in growing shorter varieties of corn. The text explains that plant specialists are working to develop shorter corn varieties in an effort to improve yields. The text points out that although greater height in corn plants can lead to more ears of corn per plant, it also makes the stalks more likely to be damaged by strong winds before there is a chance to harvest the corn. This presents a clear trade-off between potential yield (taller plants producing more ears per plant) and harvest reliability (shorter plants surviving until harvest time). Given this information, it is reasonable to infer that shorter corn varieties, while possibly producing fewer ears per plant, would be more likely to survive until harvest time. This survival advantage would result in improved yields of harvested corn because more plants would remain intact, thus offsetting the potential reduction in ears per shorter plant.
Why the other choices are wrong
Choice B
Choice B is incorrect. According to the text, greater height makes cornstalks vulnerable to snapping or being uprooted in strong winds, implying that taller plants—not shorter ones—have greater stability problems. The text provides no basis for inferring that shorter corn varieties would be more likely to be uprooted due to corn weight; in fact, the text suggests the opposite relationship between height and stability.
Choice C
Choice C is incorrect because the text doesn’t provide information about the land requirements of either shorter corn varieties or shorter wheat and rice varieties, much less make any comparisons. The text mentions that plant breeders in the 1950s and ’60s created shorter varieties of wheat and rice with improved yields and that researchers are now exploring shorter corn varieties, but it doesn’t compare land-use requirements of these crops.
Choice D
Choice D is incorrect because the idea that shorter cornstalks would yield more ears of corn would contradict the relationship between height and corn production described in the text. The text explicitly states that greater height allows individual plants to produce more ears of corn, which suggests that shorter varieties would produce fewer ears per plant, not more. The text therefore provides no basis for concluding that shorter varieties would begin developing more ears than the taller varieties currently do.