The weakest point of Darwinism was that it could not explain which of the following?

Given below are two statements regarding evolution.
Statement-$I$: Natural selection is the establishment of a phenotypic trait in changing environmental conditions.
Statement-$II$: Natural selection encourages those genes or traits that ensure highest degree of adaptive efficiency between population and its environment.
In the light of above statements, choose the most appropriate answer from the options given below.

Select the appropriate option for the founder effect.

Natural selection operates at

Industrial melanism was highlighted by

Analogous structures are a result of