Islands Are Well Known for Having Many Endemic Species-Species That

Islands are well known for having many endemic species-species that are unique to that location. What isa likely explanation for this pattern?

A) Humans bring partly or fully domesticated species with them when they arrive on islands.
B) Colonizers encounter fewer competitors on an island, so they can diversify.
C) The type of organism that is a good colonizer has more than the average amount of genetic variability, so it's more likely to speciate.
D) Islands are more complex habitats than continents are, so they have more niches for specialization.