Though New Zealand Is Relatively Close to Australia, It's Faunal

Multiple Choice

Though New Zealand is relatively close to Australia, it's faunal assemblages are quite different. For instance, there are no native marsupials in New Zealand. Which of the following best accounts for these differences?

A) New Zealand experienced a major extinction that wiped out its marsupials and other Australian fauna.
B) New Zealand was isolated from Australia during critical evolutionary times.
C) The environments of Australia and New Zealand are completely different, despite their close proximity.
D) New Zealand is an island, whereas Australia is a continent. As such, one wouldn't expect them to have the same faunal assemblages.