The correct answer to your question is Tobacco Smoke. Hope this helps you out please let me know.
Definition of Carcinogens- <span>a substance capable of causing cancer in living tissue. Also known as black smoke in the lungs.</span>
Vestigial structures<span> are often homologous to </span>structures<span> that are functioning normally in other species</span>
Without variation in the population there will be no differences in relative fitness/differential reproductive success between individuals as a result of natural selection. Without differences in relative fitness between individuals there will be no change in frequency of alleles in the population overtime.
Newtons first law of motion have a very nice day