DDT Was Once Considered a "Silver Bullet" That Would Permanently

DDT was once considered a "silver bullet" that would permanently eradicate insect pests.Instead,today DDT is largely useless against many insects.Which of the following should have occurred for this pest eradication effort to be successful in the long run?

A) Larger doses of DDT should have been applied.
B) All habitats should have received applications of DDT at about the same time.
C) The frequency of DDT application should have been higher.
D) None of the individual insects should have possessed genomes that made them resistant to DDT.