Answer:
Genetic Drift
Explanation:
Genetic drift refers to the change in the allele frequencies of the population due to some chance event. It does not include natural selection.
In the given example, a storm (a chance event) led to the arrival of ten beetles on the small island. This founder population of ten beetles exhibits a higher frequency of allele "A" than that of allele "a".
However, the death of six beetles (again, a chance event) before the production of any progeny would lead to a change in the frequencies of alleles A and a. Since the allele frequencies are changed accidentally, it represents genetic drift.