70. As discussed in the text, the fruit fly Drosophila melanogaster has an allele that confers resistance to DDT and similar insecticides. Laboratory strains of D. melanogaster have been established from flies collected in the wild in the 1930s (before the widespread use of insecticides) and the 1960s (after 20 years of DDT use). Lab strains established in the 1930s have no alleles for DDT resistance. In lab strains established in the 1960s, the frequency of the DDT-resistance allele is 37%. Which statement below is true? (A) Some fruit flies evolved resistance to DDT in order to survive. (B) The heritable trait of DDT resistance cannot change even DDT use became widespread. (C) Fruit flies became more resistant to DDT over time. (D) When DDT was widely used, fruit flies with DDT resistance had greater evolutionary fitness than fruit flies lacking DDT resistance. (E) Alleles for DDT resistance arose by mutation during the period of DDT use because of selection for pesticide resistance.