What was darwains main contribution to the theory of evolution

Darwin's main contribution to the theory of evolution was his theory of natural selection.

Explanation:

Natural selection is the phenomenon that some organisms from a particular population fit better into their environment, that is, are more likely to provide surviving offspring than less well-adapted organisms. The best adapted organisms will increasingly gain the upper hand within the population (survival of the fittest). It is thus one of the mechanisms of evolution. Mutations in, and recombinations of, the genetic material of the organisms cause the genetic variation in the population, allowing this selection.

question:  

the chart compares religious beliefs to us political party support.

religious beliefs and party support, 2012

this chart demonstrates that

a) more highly religious people supported the republican candidate, while more nonreligious people supported the democratic candidate.

b) more highly religious people supported the democratic candidate, while more nonreligious people supported the republican candidate.

c) more moderately religious people supported the republican candidate, while more nonreligious people supported the democratic candidate.

d) more moderately religious people supported the democratic candidate, while more nonreligious people supported the republican candidate.

answer: a.