Correct answer choice is :
C) Primary source document
Explanation:
In the study of history as an educational rule, the main supply is an object, document, diary, manuscript, life, recording, or the other provide knowledge that was produced at the time below study. It is an inspired supply of knowledge regarding the subject. Although several primary sources stay in camera hands, others are put in information, libraries, museums, historical societies, and special collections. These may be public or non-public. Some are linked with universities and schools, whereas others are government organizations.
Robber Barons Definition: These men earned the title of 'Robber Barons' due to their greed and ruthlessness, their unethical business practices, unscrupulous tactics and their total lack of concern for their workers, their customers or their competitors. ... The power of the Robber Barons grew.
