1 At the turn of the century, nearly eight thousand varieties of apples grew in the United States. Today, ninety-five percent of those species no longer exist. Similarly, in 1949, Chinese farmers were able to grow more than ten thousand types of wheat; by 1970—just twenty-one years later—they were able to grow only one thousand types! This narrowing and specializing trend in farming is threatening the diversity of food crops.

2 Numerous corn and potato species are already extinct. Imagine if one of the extinct potato types happened to carry a gene that is resistant to a new plant disease—that gene would now be lost to the world! Trends such as this have alerted scientists to the need for a global seed bank, to ensure that the genetic diversity of the world’s food crops is preserved for the future.
Which correctly identifies the central idea of paragraphs one and two?
A) Because of the reduction in crop varieties, global seed banks are necessary.
B) Past crop diversity supports the concept of collaborative global seed banks.
C) Global seed banks are necessary to ensure sufficient food to prevent global hunger.
D) Corn and potato crops are particularly susceptible to extinction because of plant disease.