Some Gondwanan-Type Flora and Fauna Has Been Found in Sumatra

Some Gondwanan-type flora and fauna has been found in Sumatra and Kalimantan. This can be accounted for by the

A) considerable trade, which existed for tens of thousands of years, between Australian aborigines and indigenous people of Sumatra and Kalimantan.
B) fact that all the land masses of the Indo-Pacific region were once part of Gondwana.
C) similar climatic conditions and dispersal.
D) rifting, from Gondwana, of small slivers of continent which drifted north.
E) close proximity of Sumatra and Kalimantan to Australia.