Which is true about george washington carver? a) he bought his freedom from slavery as a young man. b) he was an influential civil rights activist. c) he was a great scientist and teacher. d) he was a famous explorer. which one of the following was the most significant source of urban population growth from 1890 to 1920? a) immigration from europe b) migration from the south c) elimination of small pox d) the establishment of suburbs which invention had the effect of ending the era of the "long drives" of the late 19th century? a) barbed wire b) paved roads c) the cotton gin d) the refrigerated box car i will mark you branilest if you answer all of the question!