In the 1520s, the Spanish explorer Cortes and his armies carried the virus that causes smallpox to NorthAmerica and South America. The graphs above illustrate the death rate among both Europeans and American Indians from smallpox at that time. Which of the following statements best explains the difference in death rates?

F. People in Europe were healthier than American Indians.

G. Antibiotics were available in Europe but not in North America.

H. American Indians had never been exposed to the smallpox virus, so resistant individuals had not yet become common.

J. American Indians were exposed to a virus that was different from the virus for smallpox in Europe.