According to Neo-Darwinism,which of the following is responsible for the origin of new species?

In a small population,the frequency of alleles changes due to which of the following?

Distinguish between: Natural Selection and Inheritance of Acquired Characters.

As per the modern synthetic theory,organic evolution depends upon:

When we say 'survival of the fittest',does it mean that $(a)$ those which are fit only survive,or $(b)$ those that survive are called fit? Comment.

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.