(1) some foods need more energy to produce than others. (2) grains, for example, require the least amount of energy. (3) about one-third of a calorie of fuel is spent to produce one calorie of grain. (4) meat, however, is the most costly food to produce. (5) a single calorie of beef can require as much as 90 calories of fuel to produce. (6) besides needing more energy, meats require more land and water than do plant-based foods.
(7) to supply the demand for meat, farmers in the united states maintain several billion livestock — about four times the weight of all people in the country. (8) while this colossal herd ensures that hamburgers and hot dogs are plentiful, it also creates serious problems. (9) livestock consume ten times as much grain each day as humans. (10) if that same grain food were provided to humans, it could feed an additional 400 million people. (11) in addition to consuming valuable food, livestock produce huge quantities of waste. (12) in some states, pig farms generate lakes of toxic sewage known to make humans sick.
(13) china, the most populous nation on earth, is a country that subsists on a plant-rich diet and avoids the problems caused by livestock. (14) there, a million calories of rice—the dominant crop in the nation—can be produced pollution-free on less than 1 acre of land. (15) on the other hand, a million calories of beef would require 17 acres. (16) in a world where famine and pollution are common, the chinese diet offers a model for all nations. (17) other plant-centered diets, including the traditional mediterranean diet, are also environmentally responsible.
(18) although plant-based diets are more efficient and environmentally responsible, americans are unlikely to change their eating habits; therefore, food growers must adopt better ways to produce meat. (19) farmers must stop raising grain-fed livestock in crowded farms and instead rely on old-fashioned open-range grazing. (20) grazing requires no wasteful grain food, only grass and weeds, and forces ranchers to limit livestock numbers to what lands can safely support. (21) while this type of farming would lead to an increase in the price of meat, it would also ensure that the u. s. would have a cleaner, less destructive, and less wasteful way of producing food. (22) in addition, the energy used to grow food for livestock could be used instead to provide food for people.
which sentence best expresses the central point of the passage?
question 1 options:
a. sentence 1
b. sentence 18
c. sentence 20
d. sentence 22
the author's main purpose is to
question 9 options:
a. entertain readers with descriptions of various international diets.
b. persuade americans to adopt better farming and dietary practices.
c. inform readers about the many health dangers of all-meat diets.