WORLD HISTORY

Detailed explanation-1: -Fleas drank the blood of rats infected with the Black Death. They would then pass on the infection to humans through their bite. People in the 14th century did not realize that infected flea bites caused the plague-they thought breathing in dirty air was the cause.

Detailed explanation-2: -The black rat (Rattus rattus) is one of three rodent species, along with the house mouse (Mus musculus) and brown rat (Rattus norvegicus), to have become globally distributed as a result of its ability to live around human habitations by taking advantage of food and transportation.