Final answer:
Business leaders who were 'Robber Barons' exhibited exploitative practices, monopolistic tendencies, and ruthless competition; hence the correct answer is 'd. All of the above'.
Step-by-step explanation:
Business leaders referred to as "Robber Barons" during the industrial revolution had distinct characteristics that included exploitative practices, monopolistic tendencies, and ruthless competition. These industrialists like Jay Gould in railroads, John D. Rockefeller in oil, and others were seen as exploiting workers, bending laws, and using their wealth and power to buy out or undermine competitors to dominate industries and amass personal fortunes. Therefore, the correct answer is d. All of the above.
This behavior often contrasted with that of the "Captains of Industry," who might have had similar competitive practices but were also known for making contributions that fundamentally changed and typically improved the nation through new business models and sometimes philanthropy.