Read the excerpt from "Edward Jenner and the History of Smallpox and Vaccination.” Smallpox was introduced to Europe sometime between the fifth and seventh centuries and was frequently epidemic during the Middle Ages. The disease greatly affected the development of Western civilization. The first stages of the decline of the Roman Empire (AD 108) coincided with a large-scale epidemic: the plague of Antonine, which accounted for the deaths of almost 7 million people. The Arab expansion, the Crusades, and the discovery of the West Indies all contributed to the spread of the disease.

The author most supports his argument that smallpox devastated mankind over the centuries by providing

a historical timeline.
an alternative claim.
details of a historical incident.
interesting, partially related facts.