Use the map to answer the question.
The map shown is entitled: Fourteenth-Centurt Transmission of the Black Death. It shows the spread of the plague throughout much of northern half of the Eastern Hemisphere. It is shown spreading westward from the Yuan Khanate in southeast Asia to areas in southwest Asia and Europe.
Based on the map, what was MOST LIKELY the biggest factor in the spread of the Black Death?
A.
the expansion of Islamic empires
B.
feudal labor practices
C.
the Catholic Crusades
D.
trade between Europe and Asia