What eventually caused the Silk Road to fall apart?

A. China closed the Silk Road after they discovered spies trying to steal their secrets.
B. They fall of the Mongol Empire led to many separate powers owning the Silk Road.
C. The rise of the Mongol Empire led to an area of instability in the region.
D. The Age of Discovery made the Silk Road less useful.

D. The Age of Discovery made the Silk Road less useful.