Based on the information in "Edward Jenner and the History of Smallpox and Vaccination," how does the author support the claim that the slave trade played a role in the spread of smallpox? (A)by explaining how smallpox was brought to America

(B)by describing how smallpox was used as a weapon in America

(C)by suggesting that the disease existed wherever enslaved people traveled

(D)by discussing the presence of the disease where enslaved people originated