Which means of delivering mail went out of business in 1861 after the completion of the transcontinental telegraph?
a.
stagecoaches
b.
u. s. postal service
c.
pony express
d.
clipper ships

It is C. Pony Express

Hope this helps. :)

c. wright mills's sociological imagination suggest investigating to explain this increase?

hello,

answer: a federal government has final authority on interstate/inter provincial  and international affairs, a confederation is one where the central/national government or authority is governing body what does not have final say over the same matters. hopefully this and i will try again if you don't like this answer : )

best of luck!