genes that control factors such as size, color and shape determine the differences in

fruit. and now thatscientists have discovered how to detect different genes, farmers can hand over a young and tender branchto have its genes checked prior to planting. it works the same way as a detective checking fingerprints.once farmers know which trees are good and which are bad, they can discard the bad ones. farmers can evencreate new varieties according to their individual tastes.in the past three years, tens of thousands of tests were carded out to determine the genetic (基因的)features of fruit. zhang, a chinese scientist, showed a photo of a dna-test and pointed to the shininglines on it, saying that the lines were genetic signs that tell us what a tree's fruit will belike. for example, the ordinary pear tree bears fruit after four years. but now it only takes a month to test the dna from a young leaf and a farmer will know everything about its fruit. by mixing differenttypes of trees with suitable genes, farmers can create whatever fruit trees they want.Detecting different genes in plants is like ()

A.the examination of human finger-prints

B.the development of new varieties of fruit

C.the checking of young and tender branches

D.the distinction between bad trees and good ones