In the year 2500, five male space colonists and five female space colonists (all unrelated to each other) settle on an uninhabited Earthlike planet in the Andromeda galaxy. The colonists and their offspring randomly mate for generations. All 10 of the original colonists had free earlobes, and 2 were heterozygous for that trait. The allele for free earlobes is dominant to the allele for attached earlobes.

If four of the original colonists died before they produced offspring, the ratios of genotypes could be quite different in the subsequent generations. This is an example of?

The correct answer is genetic drift.

Explanation:

The phenomenon of changing the frequency of an allele in a specific population with time is known as genetic drift. The mentioned gene variation or the modification in the frequency of the allele is required to take place abruptly so that the phenomenon of genetic drift can take place. The environmental factors do not play an essential role in the phenomenon of genetic drift to take place.  

The process of genetic drift occurs generally due to random sampling of organisms, it illustrates the random change in the number of gene variants within a population. When the existence of the different forms of a gene, that is, alleles, enhances or reduces by chance with time within a population, the phenomenon of genetic drift occurs. Thus, the mentioned case is an illustration of genetic drift.  

the answer is:

carbon dioxide