The statement that best describes the effect of the bubonic plague on the Mongol territories is:
The bubonic plague had little effect on the Mongol territories because they had already been exposed to it.
This is accurate because the Mongol Empire had already experienced outbreaks of the plague, and the interconnectedness of their trade routes facilitated the spread of the disease. As a result, many Mongol territories were somewhat familiar with the effects of the plague.