Many Species of Finches, Tortoises, Cacti, and Iguanas Are Found

Many species of finches, tortoises, cacti, and iguanas are found on the Galápagos Islands and nowhere else in the world. Which physical attribute of these islands has played a role in permitting such unique life forms to evolve?

A) There is geographic isolation from mainland species.
B) Multiple islands exist.
C) The islands are small compared to the South American mainland.
D) Each island has its own unique environment.
E) All of the above answers describe physical attributes of the islands important in the evolution of unique life forms.