The correct answer is C) the spread of the bubonic plague.
The biggest disrupter to the social structure of Medieval Europe was the spread of the bubonic plague.
The bubonic plague was also known as the Black Death. During the 1300s, this epidemic plague killed millions of people in Europe and Asia. It entered Europe through Messina, a Sicilian port, in 1347. The ships that arrive in October of that year had the corps of dead sailors and many more were sick.