Which of the Following Enabled Humans to Migrate from Southeast

Which of the following enabled humans to migrate from Southeast Asia to Australia roughly 60,000 years ago?

A) Falling sea levels during an era of global cooling created land bridges between many of the islands of the South Pacific across which humans could trek, ultimately to Australia.
B) Humans developed sophisticated sea vessels capable of easily navigating from the Island Pacific to Australia.
C) Due to continental drift, the continents of Asia and Australia were far closer during early human migration than they are today.
D) Sophisticated political orders compelled early humans to seek out new territories for conquest and colonization.