Which is the most important factor for the evolution of a new species?

Given below are two statements.
Statement-$I$: Elimination of particular alleles from a population due to natural disasters is called genetic drift.
Statement-$II$: Sudden temporary heritable change in the gene is called point mutation.
In the light of above statements,choose the most appropriate answer from the options given below:

According to $Darwin$,fitness refers to .........

Random genetic drift in a population probably results from

Genetic drift is also known as ........

Prodigality of reproduction in Darwinism refers to: