Hello!
The correct answer to this question is C: a monopoly.
A monopoly is one company that takes over an industry, product, or service. Due to the fact that monopolies took over business in several industries, they then had the power to regulate their own prices. This was harmful to customers because they were unable to find another seller of the same product if they could not afford the monopoly's price.
Today, several companies compete in nearly every industry. This gives customers the freedom to choose which company to use/purchase through.
I hope this helps you!