Answer:
Hello, answer is A
Step-by-step explanation:
The question mention a Pacific island, so these islands in Pacific ocean are not formed by a land or ground breaking, Pacific's islands arise from the sea's bottom when lava gets in touch with the water. So, we are not talking about an orginal population which was divided (vicariance) , we are talking about an original ancestor which occupied both islands long time ago and evolved into two new species (allopatric speciation)