What Technological Advantage Led to the Vikings' Successful Conquests and Trade

What technological advantage led to the Vikings' successful conquests and trade?

A) Sophisticated ships that could travel up rivers and across open ocean waters
B) Superior metallurgy techniques that produced stronger and more durable weapons
C) The ingestion of medicinal herbs that eliminated pain during battle
D) The development of gunpowder technologies that they had learned from merchants along the Silk Road