A、Economic crisis. B、Terrorism. C、High oil price. D、Speculation. C事实细节题。本题问的是什么使食品价格上涨的情况变得更糟。短文中提到，农业之外的影响因素使情况(食品价格上涨)更加恶化：美元贬

Around the world, the food system is in crisis. Prices have rocketed: they are now higher in real terms than at any time since 1984. They could rise further still if drought lays waste to wheat harvest in Asia, as is feared. Food has played some role—how large is hard to tell—in the uprisings in the Middle East.(23)High prices are adding millions to the number who go to bed hungry each night. This is the second price increase in less than four years.(24)Companies are sounding the alarm and the G20 grouping of the world’s largest economies has put "food security" at top of its to-do list. The main reasons for high prices are temporary: drought in Russia and Argentina: floods in Canada and Pakistan: export bans by countries determined to maintain their own supplies.(25)Influences outside agriculture make matters worse: A weaker dollar makes restocking cheaper in local currencies, and dearer oil pushes up the cost of inputs. Some people mistakenly blame yet another factor: speculation. True, increased financial trading might make prices more unstable, though the evidence is weak. But trading cannot drive prices up in the long term since for every buy, there is a sell. At the moment big structural shifts, such as the growth of India, are influencing prices less than one might think. The Asian giants are demanding more food, but so far their own farmers have largely satisfied that, so they have not needed to trade much.
23. What’s the negative influence of the increase in food prices?
24. What’s the main focus of the G20 grouping?
25. What makes the increase in food prices worse?