Population because you are holding it
Answer:
A. DDT caused the mutations that led to resistance
Explanation:
Some insects that survived the application of the first frequent doses developed a tolerance and tolerance to it. For example, it has been proven that the common fly has developed DDT-resistant generators characterized by a larger size, a quinine layer less permeable to the pesticide and a greater amount of fat . A fly of this type can withstand changes between 300 and 1000 s today.
Migration and genetic drugs is like birds in the winter moving where it's warmer and the make babies to move back over where the original place is warm
I hope that helps