Let me preface this by saying I know I should be using official questions, but I bought this book in a rush for a trip where I wouldn't have great internet (powerscore books haven't arrived yet). My thoughts on the question at the bottom so as to not influence anyone before reading.

Despite five consecutive years in which global consumption of grain has been greater than global production, it is unlikely that the world is facing a near-term crisis in the food supply. The average shortfalls have been mainly due to reduced output from farms in China, which is moving from a policy of central control over agricultural production to a more market-driven model. Therefore, if demand for grain continues to fall short of supply, Chinese production of grain should increase dramatically. Which one of the following principles most helps to justify this reasoning?

A. Global markets respond more slowly than regional markets, so local rates of production usually change more rapidly than the global average.

B. When agricultural production is centrally controlled, it is unable to respond to changing demand by adjusting rates of supply.

C. Average shortfalls are most readily remedied by local increases in production.

D. When agricultural production is market-driven, it is likely to respond to rising demand by increasing production.

E. Centrally controlled agricultural production has been shown to be more inefficient than market-driven models.

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Answer/Explanation below.

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Explanation:

Correct Answer: D

When agricultural production is market-driven, it is likely to respond to rising demand by increasing production.

The speaker concludes that Chinese production will rise if demand requires it based on the premise that Chinese production is now market-driven. Clearly the author connects market-driven methods with matching supply and demand. Choice A isn't right because it isn't actually about the difference between global and regional markets but about China's transformation to a market economy. Choice B doesn't justify the conclusion but explains how things worked under China's older system. Choice C is wrong because the speaker isn't talking about local production. Choice D looks like the right answer. The speaker bases his conclusion on the principle that a market economy will respond to increased demand with increased production. Choice E isn't right. The speaker doesn't mention inefficiency or even compare a market-driven system to a centrally regulated one; he's only interested in the effects of China's transition between the two. Choice D is the best answer.

I think they swapped the words supply and demand in the conclusion and that it should read "Therefore, if supply for grain continues to fall short of demand, Chinese production of grain should increase dramatically." I know questions don't have to reflect reality, but this isn't even internally consistent. Continues should refer to the situation presented in the first sentence, but the first sentence clearly says that consumption (demand) is greater than production (supply). And the first line of the explanation also clearly says "The speaker concludes that Chinese production will rise if demand requires it", and demand would only require it if demand were greater than supply.

Thoughts?