参考答案：C

解析：[听力原文] 31-35 In most corners of the world malnutrition is plainly a matter of outright insufficiency of food for population -- where the majority of the people do not obtain enough food calories to meet minimal needs for support of physical work and for maintenance of health. Elsewhere the problem may be not one of insufficient calories but of lack of specific nutrients essential for health. In Latin America, as in other places, the dread protein deficiency disease kwashiorkor is taking its heavy toll on children’s lives. Strategic vitamins and minerals may be lacking due to traditional diets which are nutritionally imbalanced. Here people continue their eating pattern year after year without knowledge of what their dietary habits are doing to themselves and to future generation. With a basic knowledge of nutritional needs and deficiencies, efforts would be directed to finding food substitutes which could meet these needs. Mixtures of vegetable proteins, like soybeans and peanuts, could provide an abundance of cheap, useful protein where meats, eggs, and milk are not within economic reach of large groups in the population. Efforts could also be expanded on increasing the agricultural productivity in specific regions; where large areas are given over to relatively inefficient use as grazing land, the intensive production of vegetable protein crops could bring remedial nutrition to an undernourished population.

[分析]： 事实细节的找寻和判断。 根据题干中关键词cheap protein可定位到原文相关信息处Mixtures of vegetable proteins， like soybeans and peanuts，could provide an abundance of cheap，useful protein where meats，eggs，milk are not within economic reach of large groups in the population即由于经济原因买不起肉、蛋、奶的大量人口可以从蔬菜类蛋白混合物中获取丰富、便宜而有用的蛋白，大豆和花生就是很好的选择。由此可判断肉、蛋、奶的便宜的蛋白替代品可从大豆中获得。因此，C项内容是正确答案。[解题关键] 正确理解句式复杂的句子意思是解题的关键。本题中原文句式复杂，全句是复合句，where引导的是状语从句。