1. Why were leaders of "big business in the late 1800's referred to as "captains of industry" by some and "robber barons" by others?

The correct answer to this open question is the following.

Why were leaders of "big business in the late 1800s referred to as "captains of industry" by some and "robber barons" by others?

Because those men were important businessmen in that time in the United States and created huge companies that grow immensely until they were lonely competitors in their industries. That was the case of John D. Rockefeller with the Standaard Oil Company or Andrew Carnegie with the Steel Company. Other great entrepreneurial names of the time were also Henry Ford and Cornelious Vanderbilt.

On the other hand, journalists and citizens accused these men of creating monopolies and injustice corporate practices that did not allow other companies to compete in these industries. That is why some called them "robber barons."