Final answer:
The late 1800s saw the rise of monopolies and trusts in big business, with powerful families like the Rockefellers and Vanderbilts amassing fortunes and exerting influence over government. The government responded to the predatory tactics of these companies by passing laws to regulate key industries and break up monopolies.
Step-by-step explanation:
The main idea about big business in the late 1800s presented by this source is that the late 1800s saw the rise of monopolies and trusts. During this time, families such as the Rockefellers and Vanderbilts amassed fortunes and used their influence in business to control aspects of government as well. The government passed laws to regulate key industries and break up monopolies in response to the predatory tactics used by these large companies.