What are the two provided theories for what caused the Black Death?

Answer 1

The two main theories for what caused the Black Death are:

1) Bubonic Plague Theory - This theory suggests that the Black Death was caused by the bacteria Yersinia pestis. It is believed that fleas that infested rats carried the bacteria, which spread to humans through flea bites.

2) Pneumonic Plague Theory - This theory argues that the Black Death was caused by a more virulent form of the bacteria Yersinia pestis, which could be transmitted directly from person to person through airborne droplets. This form of the disease was much more deadly and spread rapidly, especially in crowded cities.