Operation on this continent, having over 1,400 stations, and employing upwards of 10,000 operators
and clerks. The number of messages passing over all the lines in
this country annually is estimated at upwards of 5,000,000,
producing a revenue of $2,000,000.
rapid communication of information to distant locations
Ο ο ο ο
0 0 0 0
the increased ability of people to work at night
-Atlantic Monthly, March 1860
rapid population growth in the western territories
The invention discussed in this article led directly to -

option d is correct. corroborated sources of historical evidence   is necessary to validate a claim about an event in history.

historians tend to use written sources, but audio and visual materials as well as artifacts are important objects that supply information to modern historians.

historical sources are usually divided into two categories: primary and secondary sources. depending on the historian's intent, some sources shift their designation. determining what type of sources toimplement, and the level of credibility and reliability of those sources, is a significant step in critical thinking for the historian.

explanation:

the first historical instance of china engaging in internationalism was during the han dynasty.[1] at the start of the han dynasty, the huns in the north were attacking the frontiers of han and trying to obtain riches. emperor wu of han wanted to gain an alliance with a country called dayuezhi so the two countries could join together and fight against the huns.[2] to obtain this alliance, emperor wu sent zhang qian to the west to establish economic and cultural connections.[2] history records that during the han dynasty there were four primary avenues of contact between china and europe. they included the northern land route, the central land route, the southern sea route, and the far southern sea route.[1] the most famous of these routes is the central land route, or the classical silk road, comprising a network of roads stretching from northwest china to the ports of syria and the black sea, which passed through the oasis of the turkestans and northern persia.[1] the silk road was significant for chinese emperors because it provided dominance over central asia by developing resources and provided new markets for the export of china's most valuable resources.[1]

the answer would be:

b. race

a. by accepting the election of president abraham lincoln in 1860 and convincing other southern states to do the same