The statement that best analyzes the effect of leadership on the collapse of the Mongol Empire is:
Disputes over leadership led to the fragmentation of the Mongol Empire into smaller khanates.
This statement highlights how internal conflicts and disagreements regarding leadership weakened the central authority of the empire, ultimately resulting in its division into smaller, less cohesive entities known as khanates. This fragmentation made the empire more vulnerable to external threats and contributed significantly to its decline.