Final answer:
Late 19th-century opponents of laissez-faire economics believed in government intervention to prevent monopolies and protect workers and consumers, which set the stage for the Progressive reforms advocating for balanced government regulation.
Step-by-step explanation:
Opponents and reformers against the laissez-faire doctrine of the late 19th century argued that a hands-off approach to economics leads to monopolies and trusts that could harm the public interest. They called for government intervention to regulate the economy, establish quality controls, and set up health and safety standards to protect consumers and workers. The turn of the 20th century saw progressive reformers, who sought a balanced approach with government regulation to ensure fair competition and prevent the harsh outcomes of unchecked industrial capitalism.