Read this excerpt from "Edward Jenner and the History of Smallpox and Vaccination.”The origin of smallpox as a natural disease is lost in prehistory. It is believed to have appeared around 10,000 BC, at the time of the first agricultural settlements in northeastern Africa. It seems plausible that it spread from there to India by means of ancient Egyptian merchants.
Answer
A
It is difficult to trace the beginnings of smallpox.
B
Smallpox was most dangerous in prehistoric times.
C
Smallpox most likely originated from farms in India.
D
It is unclear how other diseases are related to smallpox.
Explanation
The excerpt says the origin of smallpox “is lost in prehistory,” meaning it is difficult to know exactly where or when the disease began. It suggests smallpox may have appeared around 10,000 BC in northeastern Africa, but presents that as a belief rather than a certainty. Therefore, “It is difficult to trace the beginnings of smallpox” is the best choice.
AI-written and checked against the verified answer.