The effect of genetic drift increases as the population size:

Explanation

Genetic drift refers to random changes in allele frequencies within a population, which can result in the loss or fixation of alleles over time. This process is particularly influential in small populations, where the random sampling of alleles can lead to significant changes in genetic diversity. In contrast, larger populations buffer these random changes due to a higher number of alleles and individuals, making genetic drift less impactful. Thus, the correct answer is that the effect of genetic drift increases as the population size decreases. The other options are incorrect because they fail to recognize the inverse relationship between population size and the impact of genetic drift.