The correct answer is option ($2$), because the flippers of the Penguins and Dolphins perform similar function but they are not anatomically similar structures. This is example of analogous structures.

– Option ($1$) is incorrect as natural selection is a key mechanism of evolution.

– Option ($3$) is incorrect as divergent evolution results in the formation of homologous structures.

– Option ($4$) is incorrect as adaptive radiation is the process of evolution of different species in a given geographical area starting from a point and literally radiating to the other areas of geography.