What is the author's message about natural selection and the idea of "survival of the fittest"?

a.
he believes that even human beings could be overpowered by something more "fit" someday.

b.
he thinks that natural selection is possible but feels there needs to be more proof.

c.
he does not believe in these ideas at all.

d.
he thinks that human beings are the fittest, most powerful beings on earth.