Answer:
The tree falling on the smaller population will have a bigger effect on allele frequency
Step-by-step explanation:
The falling trees each killed 50 beetles. In the smaller population of 100 beetles this killed 50% of the beetles (50 out of 100). In the larger population the tree only killed 10% of the beetles (50 out of 500). Because the tree killed a higher percentage of beetles in the smaller population, it also changed the allele frequency by a bigger percent. So, genetic drift has a much bigger effect on allele frequency in smaller populations.