单选题 What's the main idea of the second paragraph?______

A、 Fossil energy was once very cheap
B、 Farms in dry areas could get cheap water
C、 Most American farmers used too much fertilizer and pesticide
D、 Mainstream American agriculture used to be wasteful of energy, water and land

【正确答案】 D

【答案解析】第二段第一句指出，相比之下，美国主流农业到目前仍然不重视对能源、水和土地的使用。