<span>an increase in the number of men voting and the concept of Manifest Destiny</span>
The correct answer is A. Technological advances such as s<em>team power, air brakes, automatica lubricators and steel tracks</em> have affected the railroads very positively, since it has made it possible that the rail network could become a safer, more efficient and more reliable means of transportation for goods.
The main cause of shays rebellion where the large amount of debt the farmers where experiencing in the 1780s. another cause is the lack of economic crisis laws in massachusetts. Some other causes where because of bad harvests economic depression and high taxes threating farmers with the loss of their farms.
C. The earliest ancestors of humans lived in Africa.