Read this excerpt: we meet at a college noted for knowledge, in a city noted for progress, in a state noted for strength, and we stand in need of all three, for we meet in an hour of change and challenge, in a decade of hope and fear, in an age of both knowledge and ignorance. the greater our knowledge increases, the greater our ignorance unfolds. john f. kennedy, "john f. kennedy address at rice university on the space effort" what is the main idea of this excerpt from kennedy's address at rice university? a. ignorance is dangerous, and we must fight against it. b. the students at this university are some of the smartest in the world. c. we are about to enter a period of extraordinary challenges. d. knowledge and strength will be important in this time of change.

Read this 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. unknown in the new world, smallpox was introduced by the spanish and portuguese conquistadors. the disease decimated the local population and was instrumental in the fall of the empires of the aztecs and the incas. similarly, on the eastern coast of north america, the disease was introduced by the early settlers and led to a decline in the native population. before it reached the new world, smallpox played a role in