Giving brainliest to correct answers only.

which of the following excerpts from "the significance of the frontier in american history' best supports the idea that the frontier created what we now refer to as a 'melting pot'?

a. an interesting illustration of the tone of frontier democracy in 1830 comes from the same debates in the virginia convention already referred to.

b. the east took a narrow view of american advance, and nearly lost these men.

c. from the close of the seventeenth century various intercolonial congresses have been called to treat with indians and establish common measures of defense.

d. first, we note that the frontier promoted the formation of a composite nationality for the american people. the coast was preponderantly english, but the later tides of continental immigration flowed across to the free lands.