The correct answer is "breaking up monopolies".
Progressivism is a philosophy which promotes the improvement of society through advancements in science, technology, economic development, and social organization.
Progressists aim to reduce the gap in inequality, which they consider is the product of laissez-faire economics and Capitalism. Several reforms were made through time following progressive ideas, including the foundation of antitrust agencies, which regulate the fusions and acquisitions of companies in order to prevent monopolies. However, many of these institutions have not been completely successful in achieving this, as it can be seen nowadays that big companies are buying out their competitors and creating pseudo-monopolies.
