Final answer:
A large population that has existed for a long period of time is likely to have the most genetic variation due to a greater amount of alleles in the gene pool and a more stable genetic structure capable of withstanding changes.
Step-by-step explanation:
The population most likely to have the most genetic variation among its members is C. a large population that has existed for a long period of time. This is because large populations have more alleles present in their gene pool, making their gene pool larger and more stable. Over time, mutations, gene flow, and natural selection contribute to genetic diversity.
Small populations, on the other hand, are more susceptible to the forces of genetic drift, which is the random fluctuation in allele frequencies from one generation to the next. In a small population, the random loss or increase of certain alleles has a much larger impact on the overall genetic makeup of the population. For example, if one individual in a population of ten fails to reproduce, 10% of the genetic variation could be lost. In contrast, the loss of one individual in a large population of hundreds or thousands has a much smaller effect on genetic variation.
Overtime, a large population that has existed for a long period will have experienced more events that introduce genetic variation, such as mutations and gene flow, and will also have a gene pool robust enough to not be significantly altered by random events or genetic drift alone.