Which of the following is not true of U.S. agriculture?
A、It is the most efficient in the world.
B、About a third of the world's food exports come from U.S. farms.
C、The use of modern farm machinery and agricultural methods has helped make U.S. farms the most efficient in the world.
D、The number of farms in the United States has increased since 1925.
【正确答案】：D
【题目解析】：本题考查美国的农业。根据课本P235可知，美国的农业是世界上最高效的；世界上大约三分之一的食品出口来自美国农场；现代农业机械和农业方法的使用使美国农场成为世界上最有效率的农场。
