Scientists theorize that australia was once part of a larger mainland area but due to plate tectonics, broke away. according to island theory, scientists can explain all but one of these occurrences as a result of australia becoming and staying an island for a very long time. that is
a) extremes in size, large or small.
b) the evolution of flightless birds.
c) the presence of relics, like the marsupials.
d) a large assortment of plant dispersal mechanisms.