This example tells us that the table below gives the allele frequencies for the big m allele in four different populations of sunflowers over 30 years. It says other than infinite population size, assume all other conditions of the Hardy-Weinberg principle are met. Then it asks, based on these data, which population do you expect to be the smallest? We have these four populations: A, B, C, and D.

We can see their allele frequencies for the big m allele here in 1990 and again 30 years later in 2020. Before we really look at the data, note that it's signaling that the condition of infinite population size is not met. So, think: what mechanism of evolution is introduced in non-infinite population sizes?

Non-infinite population sizes are affected by genetic drift, which is the random change in allele frequency. The smaller the population size, the greater the effect of genetic drift.

When examining these numbers, I search for the population with the greatest amount of change. That appears to be population C. Population C starts at an allele frequency of 0.5 and increases to an allele frequency of 1. In other words, the big m allele goes to fixation; it becomes the only allele in the population. That's the greatest amount of change, indicating that population C might be the smallest due to the significant impact of genetic drift. Therefore, I am going with C for my answer, attributing the greatest change to the significant effects expected in smaller populations due to genetic drift.

More practice after this. Give it a try.