Which of the following would most likely result in a bottleneck event, why?

Question

A. A small population of geese migrates and joins a large nesting flock of the same species. This is a bottleneck event because the small population do not bring in any new alleles to the large flock.
B. A mutation occurs in an individual poison ivy plant, doubling the number of seeds it produces. This is a bottleneck event because even though the mutation is passed down to the next generations, it does not change the frequency of any other alleles in the population.
C. A hurricane blows through a coastal swamp, killing 98% of the snails in a population. This is only a bottleneck event if there is a change in the number of alleles in the population. The 2% of the snails remaining still have the same allele frequencies as the total population.
D. A large population of broomsedge grass in a field is determined to be in Hardy-Weinberg equilibrium. This is a population bottleneck event because there is no random mating going on which increases the likelyhood that there will be a decrease in the number of alleles in the population.
E. A small population of ducks with red beaks join a large population of ducks that have no red beaks. After 5 generations the number of ducks with red beaks is reaching 50% in the population. This is a bottleneck event because there is a decrease in the number of ducks without red beaks.

Answer 1

D. A large population of broomsedge grass in a field is determined to be in Hardy-Weinberg equilibrium. This is a population bottleneck event because there is no random mating going on which increases the likelyhood that there will be a decrease in the number of alleles in the population.