Populations with --------------- individuals have greater chances...

Genetic drift refers to the random fluctuations in allele frequencies from one generation to the next. It occurs in all populations, but its effects are much more pronounced in small populations. In large populations, random variations tend to average out, keeping allele frequencies relatively stable. In contrast, small populations are highly susceptible to genetic drift, which can lead to the rapid loss or fixation of alleles purely by chance.

Among the given options, $5000-10000$ represents the smallest population size. Therefore, a population with $5000-10000$ individuals has the greatest chance of experiencing significant genetic drift.

Answer: 5000-10000.