Answer:
C. The Khans developed a postal system that allowed them to efficiently send messages throughout the empire.
Step-by-step explanation:
Communication over long distances during the height of the Mongol Empire was done through postal-relay horse stations called Örtöö. These postal relay horse station spreads throughout the empire which is the main source of communication between khans and their generals and army officers. This source of communication is the best at that time which is considered as the fastest mean of communication.