Genetic variation in a population arises due to

The peppered moth $(Biston \text{ } betularia)$, the black-coloured form became dominant over the light-coloured form of moth in England during the industrial revolution. This is an example of

Given below are the two statements.
Statement $I$: Directional isolation favours the intermediate forms and eliminates both phenotypic extremes.
Statement $II$: In directional isolation,more individuals acquire a value other than the mean character value.
In the light of the above statements,choose the correct answer from the options given below:

What do organisms exhibit to make maximum use of the environment?

Which one of the following is a cause of sympatric speciation?

How did Darwin explain the origin of species?