Answer:
A. Ways that manufacturers sought to control the marketplace.
Explanation: Merger this is a process through which business organizations come together either by one Organisation acquiring all or parts of another aimed at Ensuring the merged business will be more profitable.
Trusts are fiduciary relationship between two or more parties,where one party has the duty or responsibility to manage the property or business and the other who owns the property will be the one receiving the profit from the business.
Pools are unions or Associations of business Organisations who produce similar or different businesses especially for enhanced profit making.