Which factors contribute to the process of speciation?

Genetic drift operates only in

Following are sex ratios obtained from a given area. Which one will show an evolutionary stable strategy between males and females respectively?

Given below are two statements regarding evolution.
$Statement-I$: Isolation is the separation of a population of a particular species into smaller units, which prevents interbreeding between them.
$Statement-II$: Due to isolating mechanisms, divergence and speciation do not occur.
In the light of the above statements, choose the most appropriate answer from the options given below.

Which of the following does not illustrate the phenomenon of natural selection?

Identify the phenomenon in which a new set of population is formed from the existing population due to an excessive change in the allele frequency.