Which of the Following Theories Could Best Explain the Presence

Which of the following theories could best explain the presence of ancient humans and Asian land animals on the islands of Southeast Asia?

A) They crossed from the mainland along temporarily exposed pieces of land that are now submerged in the ocean.
B) They reached and were spread throughout the islands by seaborne traders as they went from one island to the next.
C) During periodic ice ages, glaciers extended from the coastline of the mainland to many of the islands.
D) Until an earthquake destroyed it, Huxley's Line provided a narrow land connection to the islands.