Answer:
The correct answer is E) a significant proportion of mutations are not acted upon by natural selection.
Step-by-step explanation:
The neutral theory, proposed by Motoo Kimura in 1968, proposes that part of the molecular variability produced by mutations that exists in populations is natural variability, that is, a large part of the genetic variation observed in populations is due to random fluctuation of genetic variants that are neutral, on which natural selection hardly acts, so they are not an evolutionary force since they do not contribute predominantly to natural selection and proposes genetic drift as an evolutionary mechanism.