Final answer:
The correct term for a person who became rich through ruthless and unscrupulous business practices like Vanderbilt and Carnegie is 'Robber Baron', which is option C in the multiple-choice question.
Step-by-step explanation:
A person who has become rich through ruthless and unscrupulous business practices such as Vanderbilt and Carnegie was called a robber baron. The term robber baron emerged in the late nineteenth century to describe a group of industrialists who were perceived to gain their wealth by exploiting workers and bending laws. Men like Cornelius Vanderbilt and Jay Gould became notorious for their exploitative business practices, especially in the railroad industry. Although some of these individuals, like Andrew Carnegie, later turned to philanthropy, their early business methods fit the description of robber barons.
To directly answer the multiple-choice question given, if we look at the historical figures noted for their exploitative ways in constructing their fortunes, the correct answer would be 'Robber Baron', which corresponds to option C.