The answer here is absolutely B, not E. Seems like there was enough confusion about this one to merit a good long look. So let's do it!
283. Even though its per capita food supply hardly increased during two decades, stringent rationing and planned distribution have allowed the People’s Republic of China to ensure nutritional levels of 2,000 calories per person per day for its population.
There are a number of issues here, which are worth noting before we start. There are preposition issues ("during" versus "in" versus "over"), which generally signals an idiom issue (in this case with increase, and a specified time constraint).
There are also verb tense changes (increased is past, has increased is present perfect, etc.). We solve these by looking elsewhere in the sentence for context. We have the verb "have allowed", which is present perfect. I can't think of any good reason to CHANGE tenses elsewhere in the sentence, and if you can't come up with a reason to change tenses, don't.
(A) Even though its per capita food supply hardly increased during
PROBLEM: Using the preposition "during" is incorrect. We'd have to specify a particular two decades. Also, we shouldn't use the past tense here if we can help it.
(B) Even though its per capita food supply has hardly increased in
CORRECT: Correct tense, and correct idiom "hardly increased in ten years".
(C) Despite its per capita food supply hardly increasing over
PROBLEM: Again we have a tense change (the present participle form). Also, the "over" is unclear. Do we mean "over the course of ten years" or "over ten years"?
(D) Despite there being hardly any increase in its per capita food supply during
PROBLEM: "Being" always sucks, plus it's not the best tense. Also, we have the same "during" issue as in A.
(E) Although there is hardly any increase in per capita food supply for
PROBLEM: The present tense verb "is" is wrong, both because it doesn't match the present perfect verb later, and because it turns this intro phrase into gibberish. There can't presently be hardly any increase for ten years. If you want to express something that started ten years ago and continues into the present, the correct tense choice is present perfect.
Hope that helps!
Tommy Wallach | Manhattan GMAT Instructor | San Francisco
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