The correct answer is B. Set up a network of spies to observe his enemies.
Explanation
Genghis Khan was a Mongol conqueror who stood out for having achieved the unification of many nomadic tribes located in different parts of Asia. This unification is known as the first Mongol Empire, which was noted for having a large amount of conquered territory. One of the aspects that contributed to the conquest of so much territory was the strategy that Genghis Khan used as commander of the army because he gave great importance to information about his enemies to know how to easily defeat them, for this, he established spies to infiltrate and obtain information for military purposes. So the correct answer is B. Set up a network of spies to observe his enemies.