Australia Has a Unique Flora and Fauna Because

Australia has a unique flora and fauna because

A) the aborigines selectively bred many of the plant and animal species now found there.
B) Australia has been isolated from other continents for tens of millions of years and,because of this,life has developed along different evolutionary paths.
C) as sea levels have risen and fallen it has had a land bridge connecting it to the mainland off and on.
D) unlike other continents it has only one climate.
E) it has not experienced any invasive species crises.