What Enabled India to Make Contact with the Outside World

What enabled India to make contact with the outside world in the sixth century B.C.E.?

A) Alexander the Great's conquest brought knowledge of the Mediterranean world.
B) As the Persian Empire expanded, it made territorial conquests in the Indus Valley.
C) Great expansion of overseas trade by Indian merchants and a new merchant fleet led to outside contact.
D) Significant technological improvements in sailing led to greater communication and travel.