A Scientist Is Studying the Population Genetics of a Butterfly

A scientist is studying the population genetics of a butterfly population inhabiting a group of islands off the coast of California.The mainland population has the greatest allelic diversity.Island A has lower allelic diversity than the mainland,and island B has lower diversity than island A.All the alleles found on island B are also found on island A.The allelic diversity of island C is the same as the allelic diversity of island B,but half of the alleles on island C are not found on islands A and B.Which of the following scenarios best explains this pattern?

A) All three islands were colonized from the mainland: A was colonized first,and B and C were colonized at the same time.
B) Island A was colonized from the mainland first,then butterflies from A colonized B at the same time that C was colonized from the mainland.
C) Islands A and C were colonized from the mainland at the same time,then butterflies from C colonized B.
D) Island A was colonized from the mainland first,then C was colonized from the mainland,then butterflies from C colonized B.
E) Islands B and C were colonized from the mainland at the same time,then butterflies from B colonized A.