DDT is an insecticide that was used extensivelyin the mid-1900s to kill mosquitoes. It was veryeffective at first, but after a few decades DDTbecame less effective at killing mosquitoesbecause many populations had evolvedresistance to DDT. Which of the followingconditions would biologists say was required forthe evolution of DDT resistance in a population?The mosquito population needed to evolve DDTresistance in order to avoid extinction.A few mosquitos were resistant to DDT before itwas ever used.Exposure to DDT caused specific, nonrandommutations for DDT resistance within thepopulation.Mosquitoes in the population had learned toadapt to the high levels of DDT in theenvironment.

Evolution is the change in the frequency of traits in a population over time. Due to adaptations of organisms in different climatic conditions and traits are altered and passed from one generation to another.Evolution, three types are:1. Divergent evolution - closely related groups in different habitats becoming more and more dissimilar.2. Convergent evolution - distantly related groups, converge at similar habitats, which results in the same appearances and adaptations.3. Parallel evolution - distantly related groups, converge at different locations but environmental conditions and habitats are similar, which results in independent survival.DDT is an insecticide that was used extensively in the mid-1900s to kill mosquitoes. It was very effective at first but after a few decades, DDT became less effective at killing mosquitoes because many populations had evolved resistance to DDT. The condition that biologist would say was required for the evolution of DDT resistance in a population was:Option 1: The mosquito population needed to evolve DDT resistance in order to avoid extinction. - incorrect - This option is correct as the mosquito population needed to evolve DDT resistance to avoid extinction but this is the result not the explanation of the mechanism behind their evolution.Option 2: A few mosquitos were resistant to DDT before it was ever used. - incorrect - Before DDT was used there were few mosquitos that were resistant to DDT, but this does not explain how the resistance spread in the population.Option 3: Exposure to DDT caused specific, nonrandom mutations for DDT resistance within the population. - correct - This option is correct because it explains the mechanism behind their evolution. Exposure to DDT exerts selective pressure that benefits mosquitos carrying genes ( or can say carrying mutations) conferring resistance to DDT.Option 4: Mosquitos in the pollution has learned to adapt to the high levels of DDT in the environment. - incorrect - Evolution is a genetic process and is not about conscious learning.Answer: Option 3: Exposure to DDT caused specific, nonrandom mutations for DDT resistance within the population.