Final answer:
Laissez-faire economics is the belief that capitalism works best with the least government regulation. It resulted in the rise of unregulated industries in the late 1800s-early 1900s.
Step-by-step explanation:
The belief that capitalism works best with the least government regulation, thus leading to the rise of huge industries that were not well regulated in the late 1800s-early 1900s, is known as laissez-faire economics. It is an economic policy that advocates for minimal government intervention in the free market, allowing businesses to operate without significant restrictions. During this time period, the United States experienced widespread industrialization and many businesses were able to operate with little government interference, resulting in the growth of monopolies and trusts. However, as concerns over anticompetitive behavior and exploitation of workers arose, the government began to increase regulations to protect consumers and promote fair competition.