Answer:
The most suitable answer is C. The Mongol Empire guarded roads carefully to promote trade throughout its territory.
Step-by-step explanation:
As Mongolian empire was the largest land empire at the time, spanning from China to europe, they understood the importance of Commerce and trade. Because of this, Mongolian rulers were hesitant to develop their road and transportation system and guarded in cautiously to promote trade within the empire and with the out side world.