32. 다음 빈칸에 들어갈 말로 가장 적절한 것을 고르시오.
With population growth slowing, the strongest force increasing demand for more agricultural production will be rising incomes, which are desired by practically all governments and individuals. Although richer people spend smaller proportions of their income on food, in total they consume more food ― and richer food, which contributes to various kinds of disease and debilitation. The changes in diet that usually accompany higher incomes will require relatively greater increases in the production of feed grains, rather than food grains, as foods of animal origin partly ______________________________. It takes two to six times more grain to produce food value through animals than to get the equivalent value directly from plants. It is thus quite credible to estimate that in order to meet economic and social needs within the next three to five decades, the world should be producing more than twice as much grain and agricultural products as at present, but in ways that these are accessible to the food-insecure.
* debilitation: 건강 악화