How is it believed the Black Death entered Europe?

The belief that the Black Death entered Europe via trade routes from Asia is supported by historical accounts and the nature of the disease's spread. In the mid-14th century, the bubonic plague was primarily transmitted by fleas that infested black rats, which were common on merchant ships. The interconnectedness of trade networks during this period facilitated the movement of both people and goods, effectively allowing the plague to travel with traders across vast distances.

Key trade routes, particularly those related to the Silk Road and maritime routes in the Mediterranean, are thought to have been crucial vectors for the disease. When ships arrived in European ports, they unknowingly brought infected rats and fleas, introducing the plague to new populations. This method of transmission explains the rapid spread of the Black Death across Europe, leading to widespread mortality and significant social and economic changes.

In contrast, while other options may touch on factors that could contribute to disease transmission, none match the historical evidence supporting the movement of the Black Death along established trade routes, which played a pivotal role in its entrance to Europe.