问 逻辑 新prep102

我爱伊乔

102.

In parts of South America, vitamin-A deficiency is a serious health problem, especially among children.In one region, agriculturists hope to improve nutrition by encouraging farmers to plant a new variety of sweet potato called SPK004 that is rich in beta-carotene, which the body converts into vitamin A.The plan has good chances of success, since sweet potato is a staple of the region’s diet and agriculture, and the varieties currently grown contain little beta-carotene.



Which of the following, if true, most strongly supports the prediction that the plan will succeed?



A. There are other vegetables currently grown in the region that contain more beta-carotene than the currently cultivated varieties of sweet potato do.

B. The flesh of SPK004 differs from that of the currently cultivated sweet potatoes in color and texture, so traditional foods would look somewhat different when prepared from SPK004.

C. For successful cultivation of SPK004, a soil significantly richer in nitrogen is needed than is needed for the varieties of sweet potato currently cultivated in the region.

D. There are no other varieties of sweet potato that are significantly richer in beta-carotene than SPK004 is.

E. The currently cultivated varieties of sweet potato contain no important nutrients that SPK004 lacks.

不明白D怎么不对，看了以前的帖子还是不明白。。。NN救我～～～
万谢各位CDer～

sdcar2010

Good question.  D looks like an attractive answer since it points out that SPK004 is the best source of beta-carotene for sweet potatos.  However, the argument is concerned with whether the plan will succeed, not with which plan is optimal or better than the current plan.  Therefore, D is out.

bmwsherry

what i understood was since the question has already stated that "SPK004 is rich in betacarotene, and the varieties currently grown contain little betacarotene", there is no use of stating that again. It's like because of A, so A. It's a fallacy.

DeliciaAn

看到的GmatClub里一牛人分析的，我觉得说的很对：
D. There are no other varieties of sweet potato that are significantly richer in beta-carotene than SPK004 is.

This is a particularly interesting one. We already can infer that the SPK004 sweet potato has more beta-carotene than the the traditional sweet potatoes in this region. That's the comparison that is meaningful in this argument. This answer choice provides the added information --- the SPK004 sweet potato also contains more beta-carotene than any other variety of sweet potato anywhere else --- China, Uganda, New Zealand, Alabama, etc. Well, that's interesting, but it's not particularly relevant. We already know the important comparison ---- the SPK004 sweet potato vs. sweet potatoes traditionally grown in these parts of South America. That's the part that is pertinent to the argument. The fact that the SPK004 sweet potato also contains more beta-carotene than any other variety of sweet potato in other places --- strictly speaking, this is irrelevant to the argument. Therefore, it is not a strengthener. This answer is incorrect.

Source: http://gmatclub.com/forum/in-parts-of-south-america-vitamin-a-deficiency-is-a-serious-137059.html