An astronomical unit is a unit of measurement that scientists use to determine how far something is in space
Answer:
C. The destruction of trading routes in Eurasia
Explanation:
This had a long term effecf inEurasia because mongolians were constantly invading cities and when the came to Eurasia they destroyed trading routes by killing and overpowering the cities turning it into a empire.
Density is mass per volume 
With data:
.
Hope this helps.