In the early 1950s, dr. jonas salk developed an effective vaccine for what childhood disease? a) polio eliminate b) measles c) chicken pox d) typhoid fever

Which of the following was a major outcome of european imperialism in africa after the industrial revolution? o a. the area around the suez canal experienced decades of military conflict o b. africans in the belgian congo suffered forced labor and oppression o c. the discovery of rich matural resources led to african economic prosperity. o d. europeans brought disease to central africa, killing thousands.