The correct option is C Prevalence of pesticide-resistant insects
One of the features of Darwinism is survival of the fittest. According to this, the organisms possessing favourable variations would survive, because they are the fittest to face their surroundings, while the unfit are destroyed. Darwin considered that useful variations are transmitted to the offspring, and appear more prominently in succeeding generations. After some generations, these continuous and gradual variations in the possessor would be so distinct that they form a new species. So, the pesticide-resistant insects have the ability to survive as they have resistance genes and so, they are selected by nature. Other insects lacking these genes would be killed by pesticides. Development of transgenic animals, production of 'Dolly' and the development of organs from stem cells involve human interference or selection by man, unlike the theory of Natural Selection.