Which of the following was the greatest single factor in urbanization of the gilded age?

the government made public lands available.

mechanization reduced the need for farmers.

the telegraph lines required constant attention.

railroad companies sold tracts of their land grants.

Which stanza structure does emily dickinson use in this excerpt from "hope is the thing with feathers"? hope is the thing with feathers that perches in the soul, and sings the tune without the words, and never stops at all, and sweetest in the gale is heard, and sore must be the storm that could abash the little bird that kept so many warm.